diff --git a/.fvmrc b/.fvmrc
new file mode 100644
index 0000000..e150426
--- /dev/null
+++ b/.fvmrc
@@ -0,0 +1,3 @@
+{
+  "flutter": "3.24.1"
+}
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index d597e47..a7d00e4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -31,3 +31,6 @@ build/
 **/coverage/
 **/coverage_badge.svg
 **/.test_coverage.dart
+
+# FVM
+.fvm/
diff --git a/.mergify.yml b/.mergify.yml
index ab9f8c4..c59fd53 100644
--- a/.mergify.yml
+++ b/.mergify.yml
@@ -1,45 +1,43 @@
 pull_request_rules:
-- name: "Assign author"
-  conditions: []
-  actions:
-    assign:
-      users:
-        - "{{author}}"
+  - name: 'Assign author'
+    conditions: []
+    actions:
+      assign:
+        users:
+          - '{{author}}'
 
-# Merge flow for contributors
-- name: "Request review"
-  conditions:
-    - "author!=jeroen-meijer"
-  actions:
-    request_reviews:
-      users:
-        - "jeroen-meijer"
-- name: "Merge when CI passes & has one approval"
-  conditions:
-    - "author!=jeroen-meijer"
-    - "label!=wip"
-    - "status-success~=kana_kit"
-    - "#approved-reviews-by>=1"
-  actions: 
-    merge:
-      method: squash
-      strict: smart
-      commit_message: default
+  # Merge flow for contributors
+  - name: 'Request review'
+    conditions:
+      - 'author!=jeroen-meijer'
+    actions:
+      request_reviews:
+        users:
+          - 'jeroen-meijer'
+  - name: 'Merge when CI passes & has one approval'
+    conditions:
+      - 'author!=jeroen-meijer'
+      - 'label!=wip'
+      - 'status-success~=kana_kit'
+      - '#approved-reviews-by>=1'
+    actions:
+      merge:
+        method: squash
+        commit_message: default
 
-# Merge flow for non-contributors
-- name: "Merge when CI passes"
-  conditions:
-    - "author=jeroen-meijer"
-    - "label!=wip"
-    - "status-success~=kana_kit"
-  actions: 
-    merge:
-      method: squash
-      strict: smart
-      commit_message: default
+  # Merge flow for non-contributors
+  - name: 'Merge when CI passes'
+    conditions:
+      - 'author=jeroen-meijer'
+      - 'label!=wip'
+      - 'status-success~=kana_kit'
+    actions:
+      merge:
+        method: squash
+        commit_message: default
 
-- name: Delete branch post merge
-  conditions:
-    - merged
-  actions:
-    delete_head_branch: {}
+  - name: Delete branch post merge
+    conditions:
+      - merged
+    actions:
+      delete_head_branch: {}
diff --git a/.metadata b/.metadata
deleted file mode 100644
index 4646fe6..0000000
--- a/.metadata
+++ /dev/null
@@ -1,10 +0,0 @@
-# This file tracks properties of this Flutter project.
-# Used by Flutter tool to assess capabilities and perform upgrades etc.
-#
-# This file should be version controlled and should not be manually edited.
-
-version:
-  revision: 8fe7655ed20ffd1395f68e30539a847a01a30351
-  channel: beta
-
-project_type: package
diff --git a/.vscode/settings.json b/.vscode/settings.json
index e46e621..4679403 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -7,5 +7,6 @@
     "mkdir",
     "toukyou",
     "ｚｅｎｋａｋｕ"
-  ]
-}
+  ],
+  "dart.flutterSdkPath": ".fvm/versions/3.24.1"
+}
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9fabafe..ca6cfcc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,14 @@
 ## 2.0.0
 
+- Fix シークヮーサー and シマウヮー conversion edge-cases (thanks to @Moseco and @HighLiuk)
+- Change minimum required Dart version to `2.12.0`.
+- Add CSpell spell checking config.
+- Remove `package:equatable` dependency.
+- Upgrade dependencies.
+- Upgrade all dev dependencies and linter.
+
+## 2.0.0
+
 - Add NNBD support.
 - Change minimum required Dart version to `2.12.0`.
 - Change linter to `package:very_good_analysis`.
diff --git a/analysis_options.yaml b/analysis_options.yaml
index 663e7ed..9df80aa 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -1,19 +1 @@
 include: package:very_good_analysis/analysis_options.yaml
-# linter:
-#   rules:
-#     await_only_futures: true
-#     prefer_const_constructors: true
-#     prefer_const_literals_to_create_immutables: true
-#     prefer_relative_imports: false
-#     prefer_single_quotes: true
-#     public_member_api_docs: true
-#     sort_child_properties_last: true
-#     sort_constructors_first: true
-#     unawaited_futures: true
-# analyzer:
-#   strong-mode:
-#     implicit-casts: false
-#   errors:
-#     close_sinks: ignore
-#   exclude:
-#     - '**/.test_coverage.dart'
diff --git a/codecov.yml b/codecov.yml
index 1a20e98..806952e 100644
--- a/codecov.yml
+++ b/codecov.yml
@@ -1,10 +1,10 @@
 codecov:
   require_ci_to_pass: true
-  
+
 coverage:
   precision: 3
-  range: "99...100"
+  range: '99...100'
 
 ignore:
-  - "**/*.g.dart"
-  - "lib/src/models/romanization/**"
+  - '**/*.g.dart'
+  - 'lib/src/models/romanization/**'
diff --git a/cspell.yaml b/cspell.yaml
new file mode 100644
index 0000000..c763ccf
--- /dev/null
+++ b/cspell.yaml
@@ -0,0 +1,19 @@
+ignoreWords:
+  - transform
+words:
+  - codecov
+  - hankaku
+  - hepburn
+  - HighLiuk
+  - hira
+  - initializers
+  - japanese
+  - Moseco
+  - NNBD
+  - Ōsaka
+  - pubspec
+  - romaji
+  - Tōkyō
+  - unicode
+  - zenkaku
+  - Zenkaku
diff --git a/lib/kana_kit.dart b/lib/kana_kit.dart
index bafcf0a..c352a68 100644
--- a/lib/kana_kit.dart
+++ b/lib/kana_kit.dart
@@ -50,7 +50,7 @@ class KanaKit {
   /// isRomaji('a！b&cーd'); // false (zenkaku punctuation is not allowed)
   /// ```
   bool isRomaji(String input) {
-    assert(input.isNotEmpty);
+    assert(input.isNotEmpty, 'input cannot be empty');
 
     return input.chars.every(_isCharRomaji);
   }
@@ -68,7 +68,7 @@ class KanaKit {
   /// isJapanese('A泣き虫'); // false
   /// ```
   bool isJapanese(String input) {
-    assert(input.isNotEmpty);
+    assert(input.isNotEmpty, 'input cannot be empty');
 
     return input.chars.every(_isCharJapanese);
   }
@@ -85,7 +85,7 @@ class KanaKit {
   /// isKana('あAア'); // false
   /// ```
   bool isKana(String input) {
-    assert(input.isNotEmpty);
+    assert(input.isNotEmpty, 'input cannot be empty');
 
     return input.chars.every(_isCharKana);
   }
@@ -100,7 +100,7 @@ class KanaKit {
   /// isHiragana('あア'); // false
   /// ```
   bool isHiragana(String input) {
-    assert(input.isNotEmpty);
+    assert(input.isNotEmpty, 'input cannot be empty');
 
     return input.chars.every(_isCharHiragana);
   }
@@ -116,7 +116,7 @@ class KanaKit {
   /// isKatakana('あア'); // false
   /// ```
   bool isKatakana(String input) {
-    assert(input.isNotEmpty);
+    assert(input.isNotEmpty, 'input cannot be empty');
 
     return input.chars.every(_isCharKatakana);
   }
@@ -133,7 +133,7 @@ class KanaKit {
   /// isKanji('🐸'); // false
   /// ```
   bool isKanji(String input) {
-    assert(input.isNotEmpty);
+    assert(input.isNotEmpty, 'input cannot be empty');
 
     return input.chars.every(_isCharKanji);
   }
@@ -153,12 +153,17 @@ class KanaKit {
   /// isMixed('あア'); // false
   /// ```
   bool isMixed(String input) {
-    assert(input.isNotEmpty);
+    assert(input.isNotEmpty, 'input cannot be empty');
 
     final chars = input.chars;
 
     final hasRomaji = chars.any(_isCharRomaji);
     final hasKana = chars.any(_isCharHiragana) || chars.any(_isCharKatakana);
+
+    // FIXME: This can be simplified but I can't get my brain
+    //  to do it right now.
+
+    // ignore: avoid_bool_literals_in_conditional_expressions
     final hasKanji = !(!config.passKanji ? chars.any(_isCharKanji) : false);
 
     return hasKana && hasRomaji && hasKanji;
@@ -173,6 +178,7 @@ class KanaKit {
   /// characters will be converted to uppercase characters.
   /// ignored.
   ///
+  // cspell: disable
   /// ```dart
   /// // With KanaKitConfig.upcaseKatakana == false (default)
   /// toRomaji('ひらがな　カタカナ'); // "hiragana katakana"
@@ -181,6 +187,7 @@ class KanaKit {
   /// toRomaji('ひらがな　カタカナ'); // "hiragana KATAKANA"
   /// toRomaji('げーむ　ゲーム'); // "ge-mu GEEMU"
   /// ```
+  // cspell: enable
   String toRomaji(String input) {
     if (input.isEmpty) {
       return input;
@@ -218,6 +225,7 @@ class KanaKit {
   /// The [input] `String` cannot be null. If an empty `String` is provided,
   /// an empty `String` will be returned immediately.
   ///
+  // cspell: disable
   /// ```dart
   /// toKana('onaji BUTTSUUJI'); // "おなじ ブッツウジ"
   /// toKana('ONAJI buttsuuji'); // "オナジ ぶっつうじ"
@@ -225,6 +233,7 @@ class KanaKit {
   /// toKana('batsuge-mu'); // "ばつげーむ"
   /// toKana('!?.:/,~-‘’“”[](){}'); // "！？。：・、〜ー「」『』［］（）｛｝"
   /// ```
+  // cspell: enable
   String toKana(String input) {
     if (input.isEmpty) {
       return input;
diff --git a/lib/src/checks.dart b/lib/src/checks.dart
index 4ca234d..981719f 100644
--- a/lib/src/checks.dart
+++ b/lib/src/checks.dart
@@ -5,14 +5,20 @@ bool _isCharInRange(
   required int start,
   required int end,
 }) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   final code = char.code;
   return start <= code && code <= end;
 }
 
 bool _isCharHiragana(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return _isCharLongDash(char) ||
       _isCharInRange(
@@ -23,7 +29,10 @@ bool _isCharHiragana(String char) {
 }
 
 bool _isCharKatakana(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return _isCharInRange(
     char,
@@ -33,7 +42,10 @@ bool _isCharKatakana(String char) {
 }
 
 bool _isCharKanji(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return _isCharInRange(
     char,
@@ -43,7 +55,10 @@ bool _isCharKanji(String char) {
 }
 
 bool _isCharUpperCase(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return _isCharInRange(
     char,
@@ -53,43 +68,61 @@ bool _isCharUpperCase(String char) {
 }
 
 bool _isCharKana(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return _isCharHiragana(char) || _isCharKatakana(char);
 }
 
 bool _isCharLongDash(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return char.code == prolongedSoundMark;
 }
 
 bool _isCharSlashDot(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return char.code == kanaSlashDot;
 }
 
 bool _isCharRomaji(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return romajiRanges.any((range) {
-    return _isCharInRange(char, start: range.left, end: range.right);
+    return _isCharInRange(char, start: range.$1, end: range.$2);
   });
 }
 
 bool _isCharEnglishPunctuation(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return enPunctuationRanges.any((range) {
-    return _isCharInRange(char, start: range.left, end: range.right);
+    return _isCharInRange(char, start: range.$1, end: range.$2);
   });
 }
 
 bool _isCharJapanese(String char) {
-  assert(char.length == 1);
+  assert(
+    char.length == 1,
+    'char must be a single character',
+  );
 
   return japaneseRanges.any((range) {
-    return _isCharInRange(char, start: range.left, end: range.right);
+    return _isCharInRange(char, start: range.$1, end: range.$2);
   });
 }
diff --git a/lib/src/constants.dart b/lib/src/constants.dart
index 5e03cc6..8a85ed4 100644
--- a/lib/src/constants.dart
+++ b/lib/src/constants.dart
@@ -1,9 +1,7 @@
-import 'package:kana_kit/src/utils.dart';
-
 // ignore_for_file: public_member_api_docs
 // ignore_for_file: type_annotate_public_apis
 
-// Charcodes
+// Character codes
 const latinLowercaseStart = 0x61;
 const latinLowercaseEnd = 0x7a;
 const latinUppercaseStart = 0x41;
@@ -51,44 +49,44 @@ final japaneseRanges = [
   _rareCjk,
 ];
 
-const modernEnglish = Tuple(0x0000, 0x007f);
+const modernEnglish = (0x0000, 0x007f);
 const hepburnMacronRanges = [
-  Tuple(0x0100, 0x0101), // Ā ā
-  Tuple(0x0112, 0x0113), // Ē ē
-  Tuple(0x012a, 0x012b), // Ī ī
-  Tuple(0x014c, 0x014d), // Ō ō
-  Tuple(0x016a, 0x016b), // Ū ū
+  (0x0100, 0x0101), // Ā ā
+  (0x0112, 0x0113), // Ē ē
+  (0x012a, 0x012b), // Ī ī
+  (0x014c, 0x014d), // Ō ō
+  (0x016a, 0x016b), // Ū ū
 ];
 const smartQuoteRanges = [
-  Tuple(0x2018, 0x2019), // ‘ ’
-  Tuple(0x201c, 0x201d), // “ ”
+  (0x2018, 0x2019), // ‘ ’
+  (0x201c, 0x201d), // “ ”
 ];
 
 final romajiRanges = [modernEnglish, ...hepburnMacronRanges];
 
 final enPunctuationRanges = [
-  const Tuple(0x20, 0x2f),
-  const Tuple(0x3a, 0x3f),
-  const Tuple(0x5b, 0x60),
-  const Tuple(0x7b, 0x7e),
+  const (0x20, 0x2f),
+  const (0x3a, 0x3f),
+  const (0x5b, 0x60),
+  const (0x7b, 0x7e),
   ...smartQuoteRanges,
 ];
 
 // Private
-const _zenkakuNumbers = Tuple(0xff10, 0xff19);
-const _zenkakuUppercase = Tuple(uppercaseZenkakuStart, uppercaseZenkakuEnd);
-const _zenkakuLowercase = Tuple(lowercaseZenkakuStart, lowercaseZenkakuEnd);
-const _zenkakuPunctuation_1 = Tuple(0xff01, 0xff0f);
-const _zenkakuPunctuation_2 = Tuple(0xff1a, 0xff1f);
-const _zenkakuPunctuation_3 = Tuple(0xff3b, 0xff3f);
-const _zenkakuPunctuation_4 = Tuple(0xff5b, 0xff60);
-const _zenkakuSymbolsCurrency = Tuple(0xffe0, 0xffee);
+const _zenkakuNumbers = (0xff10, 0xff19);
+const _zenkakuUppercase = (uppercaseZenkakuStart, uppercaseZenkakuEnd);
+const _zenkakuLowercase = (lowercaseZenkakuStart, lowercaseZenkakuEnd);
+const _zenkakuPunctuation_1 = (0xff01, 0xff0f);
+const _zenkakuPunctuation_2 = (0xff1a, 0xff1f);
+const _zenkakuPunctuation_3 = (0xff3b, 0xff3f);
+const _zenkakuPunctuation_4 = (0xff5b, 0xff60);
+const _zenkakuSymbolsCurrency = (0xffe0, 0xffee);
 
-const _hiraganaChars = Tuple(0x3040, 0x309f);
-const _katakanaChars = Tuple(0x30a0, 0x30ff);
-const _hankakuKatakana = Tuple(0xff66, 0xff9f);
-const _katakanaPunctuation = Tuple(0x30fb, 0x30fc);
-const _kanaPunctuation = Tuple(0xff61, 0xff65);
-const _cjkSymbolsPunctuation = Tuple(0x3000, 0x303f);
-const _commonCjk = Tuple(0x4e00, 0x9fff);
-const _rareCjk = Tuple(0x3400, 0x4dbf);
+const _hiraganaChars = (0x3040, 0x309f);
+const _katakanaChars = (0x30a0, 0x30ff);
+const _hankakuKatakana = (0xff66, 0xff9f);
+const _katakanaPunctuation = (0x30fb, 0x30fc);
+const _kanaPunctuation = (0xff61, 0xff65);
+const _cjkSymbolsPunctuation = (0x3000, 0x303f);
+const _commonCjk = (0x4e00, 0x9fff);
+const _rareCjk = (0x3400, 0x4dbf);
diff --git a/lib/src/conversions.dart b/lib/src/conversions.dart
index abdef4d..671f297 100644
--- a/lib/src/conversions.dart
+++ b/lib/src/conversions.dart
@@ -7,19 +7,28 @@ String _katakanaToHiragana(
   bool destinationIsRomaji = false,
 }) {
   bool isCharInitialLongDash(String char, int index) {
-    assert(char.length == 1);
+    assert(
+      char.length == 1,
+      'char must be a single character',
+    );
 
     return _isCharLongDash(char) && index == 0;
   }
 
   bool isCharInnerLongDash(String char, int index) {
-    assert(char.length == 1);
+    assert(
+      char.length == 1,
+      'char must be a single character',
+    );
 
     return _isCharLongDash(char) && index > 0;
   }
 
   bool isKanaAsSymbol(String char) {
-    assert(char.length == 1);
+    assert(
+      char.length == 1,
+      'char must be a single character',
+    );
 
     return ['ヶ', 'ヵ'].contains(char);
   }
@@ -38,7 +47,7 @@ String _katakanaToHiragana(
   final hiraChars = <String>[];
   for (var index = 0; index < chars.length; index++) {
     final char = chars[index];
-    // Short circuit to avoid incorrect codeshift for 'ー' and '・'.
+    // Short circuit to avoid incorrect code shift for 'ー' and '・'.
     if (_isCharSlashDot(char) ||
         isCharInitialLongDash(char, index) ||
         isKanaAsSymbol(char)) {
@@ -56,7 +65,21 @@ String _katakanaToHiragana(
         hiraChars.add('お');
         continue;
       }
-      hiraChars.add(longVowels[romaji]!);
+      // Ensure 'ヮー' => 'ゎー' => 'waa'
+      if (previousKana == 'ゎ' && char == 'ー') {
+        hiraChars
+          ..removeLast()
+          ..addAll(['わ', 'あ']);
+        continue;
+      }
+      // Try to get long vowel
+      final longVowel = longVowels[romaji];
+      // If it does not exist 'ー' is being used as a hyphen
+      if (longVowel != null) {
+        hiraChars.add(longVowel);
+      } else {
+        hiraChars.add('ー');
+      }
       continue;
     } else if (!_isCharLongDash(char) && _isCharKatakana(char)) {
       // Shift charcode.
@@ -144,9 +167,13 @@ class _MappingParser {
     if (subtree == null) {
       return null;
     }
+
     // If the next child node does not have a node value, set its node value to
     // the input.
-    return {'': tree[''] + nextChar, ...tree[nextChar]};
+    return {
+      '': (tree[''] as String) + nextChar,
+      ...(tree[nextChar] as Map<String, dynamic>),
+    };
   }
 
   List<_CharacterConversionToken> _newChunk(
@@ -157,7 +184,10 @@ class _MappingParser {
     final firstChar = remaining.chars.first;
 
     return _parse(
-      tree: {'': firstChar, ...(root[firstChar] ?? {})},
+      tree: {
+        '': firstChar,
+        ...((root[firstChar] as Map<String, dynamic>?) ?? {}),
+      },
       remaining: remaining.substring(1),
       lastCursor: currentCursor,
       currentCursor: currentCursor + 1,
diff --git a/lib/src/models/kana_kit_config.dart b/lib/src/models/kana_kit_config.dart
index 13be969..74b4af8 100644
--- a/lib/src/models/kana_kit_config.dart
+++ b/lib/src/models/kana_kit_config.dart
@@ -1,6 +1,5 @@
-import 'package:equatable/equatable.dart';
-
 import 'package:kana_kit/kana_kit.dart';
+import 'package:meta/meta.dart';
 
 /// {@template kana_kit_config}
 /// A configuration class with flags that influence
@@ -9,13 +8,16 @@ import 'package:kana_kit/kana_kit.dart';
 /// To use a default config and customize it, use [defaultConfig] and replace
 /// fields using [copyWith].
 /// {@endtemplate}
-class KanaKitConfig extends Equatable {
+@immutable
+class KanaKitConfig {
   /// {@macro kana_kit_config}
   const KanaKitConfig({
     required this.passRomaji,
     required this.passKanji,
     required this.upcaseKatakana,
-  }) : romanization = Romanization.hepburn;
+  }) :
+        // ignore: avoid_field_initializers_in_const_classes
+        romanization = Romanization.hepburn;
 
   /// The default config for `KanaKit`.
   ///
@@ -63,7 +65,7 @@ class KanaKitConfig extends Equatable {
   /// characters.
   ///
   /// ```dart
-  /// romanization: Romanizaion.hepburn,
+  /// romanization: Romanization.hepburn,
   /// ```
   final Romanization romanization;
 
@@ -81,10 +83,15 @@ class KanaKitConfig extends Equatable {
   }
 
   @override
-  List<Object> get props => [
-        passRomaji,
-        passKanji,
-        upcaseKatakana,
-        romanization,
-      ];
+  bool operator ==(covariant KanaKitConfig other) {
+    if (identical(this, other)) return true;
+
+    return other.passRomaji == passRomaji &&
+        other.passKanji == passKanji &&
+        other.upcaseKatakana == upcaseKatakana;
+  }
+
+  @override
+  int get hashCode =>
+      passRomaji.hashCode ^ passKanji.hashCode ^ upcaseKatakana.hashCode;
 }
diff --git a/lib/src/models/romanization/hepburn.dart b/lib/src/models/romanization/hepburn.dart
index 98773b2..5644ba5 100644
--- a/lib/src/models/romanization/hepburn.dart
+++ b/lib/src/models/romanization/hepburn.dart
@@ -6,57 +6,276 @@ part of 'romanization.dart';
 //            DO NOT EDIT
 // ---------------------------------
 
-const _hepburn = Romanization._(
-  name: 'Hepburn',
-  kanaToRomajiMap: {
+const _hepburnKanaToRomajiMap = {
+  'あ': {'': 'a'},
+  'い': {'': 'i'},
+  'う': {'': 'u'},
+  'え': {'': 'e'},
+  'お': {'': 'o'},
+  'か': {'': 'ka'},
+  'き': {
+    '': 'ki',
+    'ゃ': {'': 'kya'},
+    'ゅ': {'': 'kyu'},
+    'ょ': {'': 'kyo'},
+    'ぃ': {'': 'kyi'},
+    'ぇ': {'': 'kye'},
+  },
+  'く': {
+    '': 'ku',
+    'ゃ': {'': 'kya'},
+    'ゅ': {'': 'kyu'},
+    'ょ': {'': 'kyo'},
+    'ぃ': {'': 'kyi'},
+    'ぇ': {'': 'kye'},
+  },
+  'け': {'': 'ke'},
+  'こ': {'': 'ko'},
+  'さ': {'': 'sa'},
+  'し': {
+    '': 'shi',
+    'ゃ': {'': 'sha'},
+    'ゅ': {'': 'shu'},
+    'ょ': {'': 'sho'},
+    'ぃ': {'': 'shyi'},
+    'ぇ': {'': 'she'},
+  },
+  'す': {'': 'su'},
+  'せ': {'': 'se'},
+  'そ': {'': 'so'},
+  'た': {'': 'ta'},
+  'ち': {
+    '': 'chi',
+    'ゃ': {'': 'cha'},
+    'ゅ': {'': 'chu'},
+    'ょ': {'': 'cho'},
+    'ぃ': {'': 'chyi'},
+    'ぇ': {'': 'che'},
+  },
+  'つ': {'': 'tsu'},
+  'て': {'': 'te'},
+  'と': {'': 'to'},
+  'な': {'': 'na'},
+  'に': {
+    '': 'ni',
+    'ゃ': {'': 'nya'},
+    'ゅ': {'': 'nyu'},
+    'ょ': {'': 'nyo'},
+    'ぃ': {'': 'nyi'},
+    'ぇ': {'': 'nye'},
+  },
+  'ぬ': {'': 'nu'},
+  'ね': {'': 'ne'},
+  'の': {'': 'no'},
+  'は': {'': 'ha'},
+  'ひ': {
+    '': 'hi',
+    'ゃ': {'': 'hya'},
+    'ゅ': {'': 'hyu'},
+    'ょ': {'': 'hyo'},
+    'ぃ': {'': 'hyi'},
+    'ぇ': {'': 'hye'},
+  },
+  'ふ': {
+    '': 'fu',
+    'ゃ': {'': 'fya'},
+    'ゅ': {'': 'fyu'},
+    'ょ': {'': 'fyo'},
+    'ぃ': {'': 'fyi'},
+    'ぇ': {'': 'fye'},
+  },
+  'へ': {'': 'he'},
+  'ほ': {'': 'ho'},
+  'ま': {'': 'ma'},
+  'み': {
+    '': 'mi',
+    'ゃ': {'': 'mya'},
+    'ゅ': {'': 'myu'},
+    'ょ': {'': 'myo'},
+    'ぃ': {'': 'myi'},
+    'ぇ': {'': 'mye'},
+  },
+  'む': {'': 'mu'},
+  'め': {'': 'me'},
+  'も': {'': 'mo'},
+  'ら': {'': 'ra'},
+  'り': {
+    '': 'ri',
+    'ゃ': {'': 'rya'},
+    'ゅ': {'': 'ryu'},
+    'ょ': {'': 'ryo'},
+    'ぃ': {'': 'ryi'},
+    'ぇ': {'': 'rye'},
+  },
+  'る': {'': 'ru'},
+  'れ': {'': 're'},
+  'ろ': {'': 'ro'},
+  'や': {'': 'ya'},
+  'ゆ': {'': 'yu'},
+  'よ': {'': 'yo'},
+  'わ': {'': 'wa'},
+  'ゐ': {'': 'wi'},
+  'ゑ': {'': 'we'},
+  'を': {'': 'wo'},
+  'ん': {
+    '': 'n',
+    'あ': {'': "n'a"},
+    'い': {'': "n'i"},
+    'う': {'': "n'u"},
+    'え': {'': "n'e"},
+    'お': {'': "n'o"},
+    'や': {'': "n'ya"},
+    'ゆ': {'': "n'yu"},
+    'よ': {'': "n'yo"},
+  },
+  'が': {'': 'ga'},
+  'ぎ': {
+    '': 'gi',
+    'ゃ': {'': 'gya'},
+    'ゅ': {'': 'gyu'},
+    'ょ': {'': 'gyo'},
+    'ぃ': {'': 'gyi'},
+    'ぇ': {'': 'gye'},
+  },
+  'ぐ': {'': 'gu'},
+  'げ': {'': 'ge'},
+  'ご': {'': 'go'},
+  'ざ': {'': 'za'},
+  'じ': {
+    '': 'ji',
+    'ゃ': {'': 'ja'},
+    'ゅ': {'': 'ju'},
+    'ょ': {'': 'jo'},
+    'ぃ': {'': 'jyi'},
+    'ぇ': {'': 'je'},
+  },
+  'ず': {'': 'zu'},
+  'ぜ': {'': 'ze'},
+  'ぞ': {'': 'zo'},
+  'だ': {'': 'da'},
+  'ぢ': {
+    '': 'ji',
+    'ゃ': {'': 'ja'},
+    'ゅ': {'': 'ju'},
+    'ょ': {'': 'jo'},
+    'ぃ': {'': 'jyi'},
+    'ぇ': {'': 'je'},
+  },
+  'づ': {'': 'zu'},
+  'で': {'': 'de'},
+  'ど': {'': 'do'},
+  'ば': {'': 'ba'},
+  'び': {
+    '': 'bi',
+    'ゃ': {'': 'bya'},
+    'ゅ': {'': 'byu'},
+    'ょ': {'': 'byo'},
+    'ぃ': {'': 'byi'},
+    'ぇ': {'': 'bye'},
+  },
+  'ぶ': {'': 'bu'},
+  'べ': {'': 'be'},
+  'ぼ': {'': 'bo'},
+  'ぱ': {'': 'pa'},
+  'ぴ': {
+    '': 'pi',
+    'ゃ': {'': 'pya'},
+    'ゅ': {'': 'pyu'},
+    'ょ': {'': 'pyo'},
+    'ぃ': {'': 'pyi'},
+    'ぇ': {'': 'pye'},
+  },
+  'ぷ': {'': 'pu'},
+  'ぺ': {'': 'pe'},
+  'ぽ': {'': 'po'},
+  'ゔぁ': {'': 'va'},
+  'ゔぃ': {'': 'vi'},
+  'ゔ': {
+    '': 'vu',
+    'ゃ': {'': 'vya'},
+    'ゅ': {'': 'vyu'},
+    'ょ': {'': 'vyo'},
+    'ぃ': {'': 'vyi'},
+    'ぇ': {'': 'vye'},
+  },
+  'ゔぇ': {'': 've'},
+  'ゔぉ': {'': 'vo'},
+  '。': {'': '.'},
+  '、': {'': ','},
+  '：': {'': ':'},
+  '・': {'': '/'},
+  '！': {'': '!'},
+  '？': {'': '?'},
+  '〜': {'': '~'},
+  'ー': {'': '-'},
+  '「': {'': '‘'},
+  '」': {'': '’'},
+  '『': {'': '“'},
+  '』': {'': '”'},
+  '［': {'': '['},
+  '］': {'': ']'},
+  '（': {'': '('},
+  '）': {'': ')'},
+  '｛': {'': '{'},
+  '｝': {'': '}'},
+  '　': {'': ' '},
+  'ゃ': {'': 'ya'},
+  'ゅ': {'': 'yu'},
+  'ょ': {'': 'yo'},
+  'ぁ': {'': 'a'},
+  'ぃ': {'': 'i'},
+  'ぅ': {'': 'u'},
+  'ぇ': {'': 'e'},
+  'ぉ': {'': 'o'},
+  'っ': {
     'あ': {'': 'a'},
     'い': {'': 'i'},
     'う': {'': 'u'},
     'え': {'': 'e'},
     'お': {'': 'o'},
-    'か': {'': 'ka'},
+    'か': {'': 'kka'},
     'き': {
-      '': 'ki',
-      'ゃ': {'': 'kya'},
-      'ゅ': {'': 'kyu'},
-      'ょ': {'': 'kyo'},
-      'ぃ': {'': 'kyi'},
-      'ぇ': {'': 'kye'},
+      '': 'kki',
+      'ゃ': {'': 'kkya'},
+      'ゅ': {'': 'kkyu'},
+      'ょ': {'': 'kkyo'},
+      'ぃ': {'': 'kkyi'},
+      'ぇ': {'': 'kkye'},
     },
     'く': {
-      '': 'ku',
-      'ゃ': {'': 'kya'},
-      'ゅ': {'': 'kyu'},
-      'ょ': {'': 'kyo'},
-      'ぃ': {'': 'kyi'},
-      'ぇ': {'': 'kye'},
-    },
-    'け': {'': 'ke'},
-    'こ': {'': 'ko'},
-    'さ': {'': 'sa'},
+      '': 'kku',
+      'ゃ': {'': 'kkya'},
+      'ゅ': {'': 'kkyu'},
+      'ょ': {'': 'kkyo'},
+      'ぃ': {'': 'kkyi'},
+      'ぇ': {'': 'kkye'},
+    },
+    'け': {'': 'kke'},
+    'こ': {'': 'kko'},
+    'さ': {'': 'ssa'},
     'し': {
-      '': 'shi',
-      'ゃ': {'': 'sha'},
-      'ゅ': {'': 'shu'},
-      'ょ': {'': 'sho'},
-      'ぃ': {'': 'shyi'},
-      'ぇ': {'': 'she'},
-    },
-    'す': {'': 'su'},
-    'せ': {'': 'se'},
-    'そ': {'': 'so'},
-    'た': {'': 'ta'},
+      '': 'sshi',
+      'ゃ': {'': 'ssha'},
+      'ゅ': {'': 'sshu'},
+      'ょ': {'': 'ssho'},
+      'ぃ': {'': 'sshyi'},
+      'ぇ': {'': 'sshe'},
+    },
+    'す': {'': 'ssu'},
+    'せ': {'': 'sse'},
+    'そ': {'': 'sso'},
+    'た': {'': 'tta'},
     'ち': {
-      '': 'chi',
-      'ゃ': {'': 'cha'},
-      'ゅ': {'': 'chu'},
-      'ょ': {'': 'cho'},
-      'ぃ': {'': 'chyi'},
-      'ぇ': {'': 'che'},
-    },
-    'つ': {'': 'tsu'},
-    'て': {'': 'te'},
-    'と': {'': 'to'},
+      '': 'tchi',
+      'ゃ': {'': 'tcha'},
+      'ゅ': {'': 'tchu'},
+      'ょ': {'': 'tcho'},
+      'ぃ': {'': 'tchyi'},
+      'ぇ': {'': 'tche'},
+    },
+    'つ': {'': 'ttsu'},
+    'て': {'': 'tte'},
+    'と': {'': 'tto'},
     'な': {'': 'na'},
     'に': {
       '': 'ni',
@@ -69,139 +288,129 @@ const _hepburn = Romanization._(
     'ぬ': {'': 'nu'},
     'ね': {'': 'ne'},
     'の': {'': 'no'},
-    'は': {'': 'ha'},
+    'は': {'': 'hha'},
     'ひ': {
-      '': 'hi',
-      'ゃ': {'': 'hya'},
-      'ゅ': {'': 'hyu'},
-      'ょ': {'': 'hyo'},
-      'ぃ': {'': 'hyi'},
-      'ぇ': {'': 'hye'},
+      '': 'hhi',
+      'ゃ': {'': 'hhya'},
+      'ゅ': {'': 'hhyu'},
+      'ょ': {'': 'hhyo'},
+      'ぃ': {'': 'hhyi'},
+      'ぇ': {'': 'hhye'},
     },
     'ふ': {
-      '': 'fu',
-      'ゃ': {'': 'fya'},
-      'ゅ': {'': 'fyu'},
-      'ょ': {'': 'fyo'},
-      'ぃ': {'': 'fyi'},
-      'ぇ': {'': 'fye'},
-    },
-    'へ': {'': 'he'},
-    'ほ': {'': 'ho'},
-    'ま': {'': 'ma'},
+      '': 'ffu',
+      'ゃ': {'': 'ffya'},
+      'ゅ': {'': 'ffyu'},
+      'ょ': {'': 'ffyo'},
+      'ぃ': {'': 'ffyi'},
+      'ぇ': {'': 'ffye'},
+    },
+    'へ': {'': 'hhe'},
+    'ほ': {'': 'hho'},
+    'ま': {'': 'mma'},
     'み': {
-      '': 'mi',
-      'ゃ': {'': 'mya'},
-      'ゅ': {'': 'myu'},
-      'ょ': {'': 'myo'},
-      'ぃ': {'': 'myi'},
-      'ぇ': {'': 'mye'},
-    },
-    'む': {'': 'mu'},
-    'め': {'': 'me'},
-    'も': {'': 'mo'},
-    'ら': {'': 'ra'},
+      '': 'mmi',
+      'ゃ': {'': 'mmya'},
+      'ゅ': {'': 'mmyu'},
+      'ょ': {'': 'mmyo'},
+      'ぃ': {'': 'mmyi'},
+      'ぇ': {'': 'mmye'},
+    },
+    'む': {'': 'mmu'},
+    'め': {'': 'mme'},
+    'も': {'': 'mmo'},
+    'ら': {'': 'rra'},
     'り': {
-      '': 'ri',
-      'ゃ': {'': 'rya'},
-      'ゅ': {'': 'ryu'},
-      'ょ': {'': 'ryo'},
-      'ぃ': {'': 'ryi'},
-      'ぇ': {'': 'rye'},
-    },
-    'る': {'': 'ru'},
-    'れ': {'': 're'},
-    'ろ': {'': 'ro'},
+      '': 'rri',
+      'ゃ': {'': 'rrya'},
+      'ゅ': {'': 'rryu'},
+      'ょ': {'': 'rryo'},
+      'ぃ': {'': 'rryi'},
+      'ぇ': {'': 'rrye'},
+    },
+    'る': {'': 'rru'},
+    'れ': {'': 'rre'},
+    'ろ': {'': 'rro'},
     'や': {'': 'ya'},
     'ゆ': {'': 'yu'},
     'よ': {'': 'yo'},
-    'わ': {'': 'wa'},
-    'ゐ': {'': 'wi'},
-    'ゑ': {'': 'we'},
-    'を': {'': 'wo'},
-    'ん': {
-      '': 'n',
-      'あ': {'': "n'a"},
-      'い': {'': "n'i"},
-      'う': {'': "n'u"},
-      'え': {'': "n'e"},
-      'お': {'': "n'o"},
-      'や': {'': "n'ya"},
-      'ゆ': {'': "n'yu"},
-      'よ': {'': "n'yo"},
-    },
-    'が': {'': 'ga'},
+    'わ': {'': 'wwa'},
+    'ゐ': {'': 'wwi'},
+    'ゑ': {'': 'wwe'},
+    'を': {'': 'wwo'},
+    'ん': {'': 'n'},
+    'が': {'': 'gga'},
     'ぎ': {
-      '': 'gi',
-      'ゃ': {'': 'gya'},
-      'ゅ': {'': 'gyu'},
-      'ょ': {'': 'gyo'},
-      'ぃ': {'': 'gyi'},
-      'ぇ': {'': 'gye'},
-    },
-    'ぐ': {'': 'gu'},
-    'げ': {'': 'ge'},
-    'ご': {'': 'go'},
-    'ざ': {'': 'za'},
+      '': 'ggi',
+      'ゃ': {'': 'ggya'},
+      'ゅ': {'': 'ggyu'},
+      'ょ': {'': 'ggyo'},
+      'ぃ': {'': 'ggyi'},
+      'ぇ': {'': 'ggye'},
+    },
+    'ぐ': {'': 'ggu'},
+    'げ': {'': 'gge'},
+    'ご': {'': 'ggo'},
+    'ざ': {'': 'zza'},
     'じ': {
-      '': 'ji',
-      'ゃ': {'': 'ja'},
-      'ゅ': {'': 'ju'},
-      'ょ': {'': 'jo'},
-      'ぃ': {'': 'jyi'},
-      'ぇ': {'': 'je'},
-    },
-    'ず': {'': 'zu'},
-    'ぜ': {'': 'ze'},
-    'ぞ': {'': 'zo'},
-    'だ': {'': 'da'},
+      '': 'jji',
+      'ゃ': {'': 'jja'},
+      'ゅ': {'': 'jju'},
+      'ょ': {'': 'jjo'},
+      'ぃ': {'': 'jjyi'},
+      'ぇ': {'': 'jje'},
+    },
+    'ず': {'': 'zzu'},
+    'ぜ': {'': 'zze'},
+    'ぞ': {'': 'zzo'},
+    'だ': {'': 'dda'},
     'ぢ': {
-      '': 'ji',
-      'ゃ': {'': 'ja'},
-      'ゅ': {'': 'ju'},
-      'ょ': {'': 'jo'},
-      'ぃ': {'': 'jyi'},
-      'ぇ': {'': 'je'},
-    },
-    'づ': {'': 'zu'},
-    'で': {'': 'de'},
-    'ど': {'': 'do'},
-    'ば': {'': 'ba'},
+      '': 'jji',
+      'ゃ': {'': 'jja'},
+      'ゅ': {'': 'jju'},
+      'ょ': {'': 'jjo'},
+      'ぃ': {'': 'jjyi'},
+      'ぇ': {'': 'jje'},
+    },
+    'づ': {'': 'zzu'},
+    'で': {'': 'dde'},
+    'ど': {'': 'ddo'},
+    'ば': {'': 'bba'},
     'び': {
-      '': 'bi',
-      'ゃ': {'': 'bya'},
-      'ゅ': {'': 'byu'},
-      'ょ': {'': 'byo'},
-      'ぃ': {'': 'byi'},
-      'ぇ': {'': 'bye'},
-    },
-    'ぶ': {'': 'bu'},
-    'べ': {'': 'be'},
-    'ぼ': {'': 'bo'},
-    'ぱ': {'': 'pa'},
+      '': 'bbi',
+      'ゃ': {'': 'bbya'},
+      'ゅ': {'': 'bbyu'},
+      'ょ': {'': 'bbyo'},
+      'ぃ': {'': 'bbyi'},
+      'ぇ': {'': 'bbye'},
+    },
+    'ぶ': {'': 'bbu'},
+    'べ': {'': 'bbe'},
+    'ぼ': {'': 'bbo'},
+    'ぱ': {'': 'ppa'},
     'ぴ': {
-      '': 'pi',
-      'ゃ': {'': 'pya'},
-      'ゅ': {'': 'pyu'},
-      'ょ': {'': 'pyo'},
-      'ぃ': {'': 'pyi'},
-      'ぇ': {'': 'pye'},
-    },
-    'ぷ': {'': 'pu'},
-    'ぺ': {'': 'pe'},
-    'ぽ': {'': 'po'},
-    'ゔぁ': {'': 'va'},
-    'ゔぃ': {'': 'vi'},
+      '': 'ppi',
+      'ゃ': {'': 'ppya'},
+      'ゅ': {'': 'ppyu'},
+      'ょ': {'': 'ppyo'},
+      'ぃ': {'': 'ppyi'},
+      'ぇ': {'': 'ppye'},
+    },
+    'ぷ': {'': 'ppu'},
+    'ぺ': {'': 'ppe'},
+    'ぽ': {'': 'ppo'},
+    'ゔぁ': {'': 'vva'},
+    'ゔぃ': {'': 'vvi'},
     'ゔ': {
-      '': 'vu',
-      'ゃ': {'': 'vya'},
-      'ゅ': {'': 'vyu'},
-      'ょ': {'': 'vyo'},
-      'ぃ': {'': 'vyi'},
-      'ぇ': {'': 'vye'},
-    },
-    'ゔぇ': {'': 've'},
-    'ゔぉ': {'': 'vo'},
+      '': 'vvu',
+      'ゃ': {'': 'vvya'},
+      'ゅ': {'': 'vvyu'},
+      'ょ': {'': 'vvyo'},
+      'ぃ': {'': 'vvyi'},
+      'ぇ': {'': 'vvye'},
+    },
+    'ゔぇ': {'': 'vve'},
+    'ゔぉ': {'': 'vvo'},
     '。': {'': '.'},
     '、': {'': ','},
     '：': {'': ':'},
@@ -229,1001 +438,789 @@ const _hepburn = Romanization._(
     'ぅ': {'': 'u'},
     'ぇ': {'': 'e'},
     'ぉ': {'': 'o'},
-    'っ': {
-      'あ': {'': 'a'},
-      'い': {'': 'i'},
-      'う': {'': 'u'},
-      'え': {'': 'e'},
-      'お': {'': 'o'},
-      'か': {'': 'kka'},
-      'き': {
-        '': 'kki',
-        'ゃ': {'': 'kkya'},
-        'ゅ': {'': 'kkyu'},
-        'ょ': {'': 'kkyo'},
-        'ぃ': {'': 'kkyi'},
-        'ぇ': {'': 'kkye'},
-      },
-      'く': {
-        '': 'kku',
-        'ゃ': {'': 'kkya'},
-        'ゅ': {'': 'kkyu'},
-        'ょ': {'': 'kkyo'},
-        'ぃ': {'': 'kkyi'},
-        'ぇ': {'': 'kkye'},
-      },
-      'け': {'': 'kke'},
-      'こ': {'': 'kko'},
-      'さ': {'': 'ssa'},
-      'し': {
-        '': 'sshi',
-        'ゃ': {'': 'ssha'},
-        'ゅ': {'': 'sshu'},
-        'ょ': {'': 'ssho'},
-        'ぃ': {'': 'sshyi'},
-        'ぇ': {'': 'sshe'},
-      },
-      'す': {'': 'ssu'},
-      'せ': {'': 'sse'},
-      'そ': {'': 'sso'},
-      'た': {'': 'tta'},
-      'ち': {
-        '': 'tchi',
-        'ゃ': {'': 'tcha'},
-        'ゅ': {'': 'tchu'},
-        'ょ': {'': 'tcho'},
-        'ぃ': {'': 'tchyi'},
-        'ぇ': {'': 'tche'},
-      },
-      'つ': {'': 'ttsu'},
-      'て': {'': 'tte'},
-      'と': {'': 'tto'},
-      'な': {'': 'na'},
-      'に': {
-        '': 'ni',
-        'ゃ': {'': 'nya'},
-        'ゅ': {'': 'nyu'},
-        'ょ': {'': 'nyo'},
-        'ぃ': {'': 'nyi'},
-        'ぇ': {'': 'nye'},
-      },
-      'ぬ': {'': 'nu'},
-      'ね': {'': 'ne'},
-      'の': {'': 'no'},
-      'は': {'': 'hha'},
-      'ひ': {
-        '': 'hhi',
-        'ゃ': {'': 'hhya'},
-        'ゅ': {'': 'hhyu'},
-        'ょ': {'': 'hhyo'},
-        'ぃ': {'': 'hhyi'},
-        'ぇ': {'': 'hhye'},
-      },
-      'ふ': {
-        '': 'ffu',
-        'ゃ': {'': 'ffya'},
-        'ゅ': {'': 'ffyu'},
-        'ょ': {'': 'ffyo'},
-        'ぃ': {'': 'ffyi'},
-        'ぇ': {'': 'ffye'},
-      },
-      'へ': {'': 'hhe'},
-      'ほ': {'': 'hho'},
-      'ま': {'': 'mma'},
-      'み': {
-        '': 'mmi',
-        'ゃ': {'': 'mmya'},
-        'ゅ': {'': 'mmyu'},
-        'ょ': {'': 'mmyo'},
-        'ぃ': {'': 'mmyi'},
-        'ぇ': {'': 'mmye'},
-      },
-      'む': {'': 'mmu'},
-      'め': {'': 'mme'},
-      'も': {'': 'mmo'},
-      'ら': {'': 'rra'},
-      'り': {
-        '': 'rri',
-        'ゃ': {'': 'rrya'},
-        'ゅ': {'': 'rryu'},
-        'ょ': {'': 'rryo'},
-        'ぃ': {'': 'rryi'},
-        'ぇ': {'': 'rrye'},
-      },
-      'る': {'': 'rru'},
-      'れ': {'': 'rre'},
-      'ろ': {'': 'rro'},
-      'や': {'': 'ya'},
-      'ゆ': {'': 'yu'},
-      'よ': {'': 'yo'},
-      'わ': {'': 'wwa'},
-      'ゐ': {'': 'wwi'},
-      'ゑ': {'': 'wwe'},
-      'を': {'': 'wwo'},
-      'ん': {'': 'n'},
-      'が': {'': 'gga'},
-      'ぎ': {
-        '': 'ggi',
-        'ゃ': {'': 'ggya'},
-        'ゅ': {'': 'ggyu'},
-        'ょ': {'': 'ggyo'},
-        'ぃ': {'': 'ggyi'},
-        'ぇ': {'': 'ggye'},
-      },
-      'ぐ': {'': 'ggu'},
-      'げ': {'': 'gge'},
-      'ご': {'': 'ggo'},
-      'ざ': {'': 'zza'},
-      'じ': {
-        '': 'jji',
-        'ゃ': {'': 'jja'},
-        'ゅ': {'': 'jju'},
-        'ょ': {'': 'jjo'},
-        'ぃ': {'': 'jjyi'},
-        'ぇ': {'': 'jje'},
-      },
-      'ず': {'': 'zzu'},
-      'ぜ': {'': 'zze'},
-      'ぞ': {'': 'zzo'},
-      'だ': {'': 'dda'},
-      'ぢ': {
-        '': 'jji',
-        'ゃ': {'': 'jja'},
-        'ゅ': {'': 'jju'},
-        'ょ': {'': 'jjo'},
-        'ぃ': {'': 'jjyi'},
-        'ぇ': {'': 'jje'},
-      },
-      'づ': {'': 'zzu'},
-      'で': {'': 'dde'},
-      'ど': {'': 'ddo'},
-      'ば': {'': 'bba'},
-      'び': {
-        '': 'bbi',
-        'ゃ': {'': 'bbya'},
-        'ゅ': {'': 'bbyu'},
-        'ょ': {'': 'bbyo'},
-        'ぃ': {'': 'bbyi'},
-        'ぇ': {'': 'bbye'},
-      },
-      'ぶ': {'': 'bbu'},
-      'べ': {'': 'bbe'},
-      'ぼ': {'': 'bbo'},
-      'ぱ': {'': 'ppa'},
-      'ぴ': {
-        '': 'ppi',
-        'ゃ': {'': 'ppya'},
-        'ゅ': {'': 'ppyu'},
-        'ょ': {'': 'ppyo'},
-        'ぃ': {'': 'ppyi'},
-        'ぇ': {'': 'ppye'},
-      },
-      'ぷ': {'': 'ppu'},
-      'ぺ': {'': 'ppe'},
-      'ぽ': {'': 'ppo'},
-      'ゔぁ': {'': 'vva'},
-      'ゔぃ': {'': 'vvi'},
-      'ゔ': {
-        '': 'vvu',
-        'ゃ': {'': 'vvya'},
-        'ゅ': {'': 'vvyu'},
-        'ょ': {'': 'vvyo'},
-        'ぃ': {'': 'vvyi'},
-        'ぇ': {'': 'vvye'},
-      },
-      'ゔぇ': {'': 'vve'},
-      'ゔぉ': {'': 'vvo'},
-      '。': {'': '.'},
-      '、': {'': ','},
-      '：': {'': ':'},
-      '・': {'': '/'},
-      '！': {'': '!'},
-      '？': {'': '?'},
-      '〜': {'': '~'},
-      'ー': {'': '-'},
-      '「': {'': '‘'},
-      '」': {'': '’'},
-      '『': {'': '“'},
-      '』': {'': '”'},
-      '［': {'': '['},
-      '］': {'': ']'},
-      '（': {'': '('},
-      '）': {'': ')'},
-      '｛': {'': '{'},
-      '｝': {'': '}'},
-      '　': {'': ' '},
-      'ゃ': {'': 'ya'},
-      'ゅ': {'': 'yu'},
-      'ょ': {'': 'yo'},
-      'ぁ': {'': 'a'},
-      'ぃ': {'': 'i'},
-      'ぅ': {'': 'u'},
-      'ぇ': {'': 'e'},
-      'ぉ': {'': 'o'},
-      '': ''
-    },
+    '': '',
   },
-  romajiToKanaMap: {
-    'a': {'': 'あ'},
-    'i': {'': 'い'},
-    'u': {'': 'う'},
-    'e': {'': 'え'},
-    'o': {'': 'お'},
+};
+const _hepburnRomajiToKanaMap = {
+  'a': {'': 'あ'},
+  'i': {'': 'い'},
+  'u': {'': 'う'},
+  'e': {'': 'え'},
+  'o': {'': 'お'},
+  'k': {
+    'a': {'': 'か'},
+    'i': {'': 'き'},
+    'u': {'': 'く'},
+    'e': {'': 'け'},
+    'o': {'': 'こ'},
+    'y': {
+      'a': {'': 'きゃ'},
+      'i': {'': 'きぃ'},
+      'u': {'': 'きゅ'},
+      'e': {'': 'きぇ'},
+      'o': {'': 'きょ'},
+    },
+    'w': {
+      'a': {'': 'くぁ'},
+    },
     'k': {
-      'a': {'': 'か'},
-      'i': {'': 'き'},
-      'u': {'': 'く'},
-      'e': {'': 'け'},
-      'o': {'': 'こ'},
+      'a': {'': 'っか'},
+      'i': {'': 'っき'},
+      'u': {'': 'っく'},
+      'e': {'': 'っけ'},
+      'o': {'': 'っこ'},
       'y': {
-        'a': {'': 'きゃ'},
-        'i': {'': 'きぃ'},
-        'u': {'': 'きゅ'},
-        'e': {'': 'きぇ'},
-        'o': {'': 'きょ'}
+        'a': {'': 'っきゃ'},
+        'i': {'': 'っきぃ'},
+        'u': {'': 'っきゅ'},
+        'e': {'': 'っきぇ'},
+        'o': {'': 'っきょ'},
       },
       'w': {
-        'a': {'': 'くぁ'}
+        'a': {'': 'っくぁ'},
       },
-      'k': {
-        'a': {'': 'っか'},
-        'i': {'': 'っき'},
-        'u': {'': 'っく'},
-        'e': {'': 'っけ'},
-        'o': {'': 'っこ'},
-        'y': {
-          'a': {'': 'っきゃ'},
-          'i': {'': 'っきぃ'},
-          'u': {'': 'っきゅ'},
-          'e': {'': 'っきぇ'},
-          'o': {'': 'っきょ'}
-        },
-        'w': {
-          'a': {'': 'っくぁ'}
-        }
-      }
     },
-    's': {
-      'a': {'': 'さ'},
+  },
+  's': {
+    'a': {'': 'さ'},
+    'i': {'': 'し'},
+    'u': {'': 'す'},
+    'e': {'': 'せ'},
+    'o': {'': 'そ'},
+    'y': {
+      'a': {'': 'しゃ'},
+      'i': {'': 'しぃ'},
+      'u': {'': 'しゅ'},
+      'e': {'': 'しぇ'},
+      'o': {'': 'しょ'},
+    },
+    'w': {
+      'a': {'': 'すぁ'},
+      'i': {'': 'すぃ'},
+      'u': {'': 'すぅ'},
+      'e': {'': 'すぇ'},
+      'o': {'': 'すぉ'},
+    },
+    'h': {
+      'a': {'': 'しゃ'},
       'i': {'': 'し'},
-      'u': {'': 'す'},
-      'e': {'': 'せ'},
-      'o': {'': 'そ'},
+      'u': {'': 'しゅ'},
+      'e': {'': 'しぇ'},
+      'o': {'': 'しょ'},
       'y': {
         'a': {'': 'しゃ'},
         'i': {'': 'しぃ'},
         'u': {'': 'しゅ'},
         'e': {'': 'しぇ'},
-        'o': {'': 'しょ'}
+        'o': {'': 'しょ'},
+      },
+    },
+    's': {
+      'a': {'': 'っさ'},
+      'i': {'': 'っし'},
+      'u': {'': 'っす'},
+      'e': {'': 'っせ'},
+      'o': {'': 'っそ'},
+      'y': {
+        'a': {'': 'っしゃ'},
+        'i': {'': 'っしぃ'},
+        'u': {'': 'っしゅ'},
+        'e': {'': 'っしぇ'},
+        'o': {'': 'っしょ'},
       },
       'w': {
-        'a': {'': 'すぁ'},
-        'i': {'': 'すぃ'},
-        'u': {'': 'すぅ'},
-        'e': {'': 'すぇ'},
-        'o': {'': 'すぉ'}
+        'a': {'': 'っすぁ'},
+        'i': {'': 'っすぃ'},
+        'u': {'': 'っすぅ'},
+        'e': {'': 'っすぇ'},
+        'o': {'': 'っすぉ'},
       },
       'h': {
-        'a': {'': 'しゃ'},
-        'i': {'': 'し'},
-        'u': {'': 'しゅ'},
-        'e': {'': 'しぇ'},
-        'o': {'': 'しょ'},
-        'y': {
-          'a': {'': 'しゃ'},
-          'i': {'': 'しぃ'},
-          'u': {'': 'しゅ'},
-          'e': {'': 'しぇ'},
-          'o': {'': 'しょ'}
-        }
-      },
-      's': {
-        'a': {'': 'っさ'},
+        'a': {'': 'っしゃ'},
         'i': {'': 'っし'},
-        'u': {'': 'っす'},
-        'e': {'': 'っせ'},
-        'o': {'': 'っそ'},
+        'u': {'': 'っしゅ'},
+        'e': {'': 'っしぇ'},
+        'o': {'': 'っしょ'},
         'y': {
           'a': {'': 'っしゃ'},
           'i': {'': 'っしぃ'},
           'u': {'': 'っしゅ'},
           'e': {'': 'っしぇ'},
-          'o': {'': 'っしょ'}
-        },
-        'w': {
-          'a': {'': 'っすぁ'},
-          'i': {'': 'っすぃ'},
-          'u': {'': 'っすぅ'},
-          'e': {'': 'っすぇ'},
-          'o': {'': 'っすぉ'}
-        },
-        'h': {
-          'a': {'': 'っしゃ'},
-          'i': {'': 'っし'},
-          'u': {'': 'っしゅ'},
-          'e': {'': 'っしぇ'},
           'o': {'': 'っしょ'},
-          'y': {
-            'a': {'': 'っしゃ'},
-            'i': {'': 'っしぃ'},
-            'u': {'': 'っしゅ'},
-            'e': {'': 'っしぇ'},
-            'o': {'': 'っしょ'}
-          }
-        }
-      }
+        },
+      },
     },
-    't': {
-      'a': {'': 'た'},
-      'i': {'': 'ち'},
+  },
+  't': {
+    'a': {'': 'た'},
+    'i': {'': 'ち'},
+    'u': {'': 'つ'},
+    'e': {'': 'て'},
+    'o': {'': 'と'},
+    'y': {
+      'a': {'': 'ちゃ'},
+      'i': {'': 'ちぃ'},
+      'u': {'': 'ちゅ'},
+      'e': {'': 'ちぇ'},
+      'o': {'': 'ちょ'},
+    },
+    's': {
+      'a': {'': 'つぁ'},
+      'i': {'': 'つぃ'},
       'u': {'': 'つ'},
-      'e': {'': 'て'},
-      'o': {'': 'と'},
+      'e': {'': 'つぇ'},
+      'o': {'': 'つぉ'},
+    },
+    'h': {
+      'a': {'': 'てゃ'},
+      'i': {'': 'てぃ'},
+      'u': {'': 'てゅ'},
+      'e': {'': 'てぇ'},
+      'o': {'': 'てょ'},
+    },
+    'w': {
+      'a': {'': 'とぁ'},
+      'i': {'': 'とぃ'},
+      'u': {'': 'とぅ'},
+      'e': {'': 'とぇ'},
+      'o': {'': 'とぉ'},
+    },
+    't': {
+      'a': {'': 'った'},
+      'i': {'': 'っち'},
+      'u': {'': 'っつ'},
+      'e': {'': 'って'},
+      'o': {'': 'っと'},
       'y': {
-        'a': {'': 'ちゃ'},
-        'i': {'': 'ちぃ'},
-        'u': {'': 'ちゅ'},
-        'e': {'': 'ちぇ'},
-        'o': {'': 'ちょ'}
+        'a': {'': 'っちゃ'},
+        'i': {'': 'っちぃ'},
+        'u': {'': 'っちゅ'},
+        'e': {'': 'っちぇ'},
+        'o': {'': 'っちょ'},
       },
       's': {
-        'a': {'': 'つぁ'},
-        'i': {'': 'つぃ'},
-        'u': {'': 'つ'},
-        'e': {'': 'つぇ'},
-        'o': {'': 'つぉ'}
+        'a': {'': 'っつぁ'},
+        'i': {'': 'っつぃ'},
+        'u': {'': 'っつ'},
+        'e': {'': 'っつぇ'},
+        'o': {'': 'っつぉ'},
       },
       'h': {
-        'a': {'': 'てゃ'},
-        'i': {'': 'てぃ'},
-        'u': {'': 'てゅ'},
-        'e': {'': 'てぇ'},
-        'o': {'': 'てょ'}
+        'a': {'': 'ってゃ'},
+        'i': {'': 'ってぃ'},
+        'u': {'': 'ってゅ'},
+        'e': {'': 'ってぇ'},
+        'o': {'': 'ってょ'},
       },
       'w': {
-        'a': {'': 'とぁ'},
-        'i': {'': 'とぃ'},
-        'u': {'': 'とぅ'},
-        'e': {'': 'とぇ'},
-        'o': {'': 'とぉ'}
-      },
-      't': {
-        'a': {'': 'った'},
-        'i': {'': 'っち'},
-        'u': {'': 'っつ'},
-        'e': {'': 'って'},
-        'o': {'': 'っと'},
-        'y': {
-          'a': {'': 'っちゃ'},
-          'i': {'': 'っちぃ'},
-          'u': {'': 'っちゅ'},
-          'e': {'': 'っちぇ'},
-          'o': {'': 'っちょ'}
-        },
-        's': {
-          'a': {'': 'っつぁ'},
-          'i': {'': 'っつぃ'},
-          'u': {'': 'っつ'},
-          'e': {'': 'っつぇ'},
-          'o': {'': 'っつぉ'}
-        },
-        'h': {
-          'a': {'': 'ってゃ'},
-          'i': {'': 'ってぃ'},
-          'u': {'': 'ってゅ'},
-          'e': {'': 'ってぇ'},
-          'o': {'': 'ってょ'}
-        },
-        'w': {
-          'a': {'': 'っとぁ'},
-          'i': {'': 'っとぃ'},
-          'u': {'': 'っとぅ'},
-          'e': {'': 'っとぇ'},
-          'o': {'': 'っとぉ'}
-        }
-      }
-    },
-    'n': {
-      'a': {'': 'な'},
-      'i': {'': 'に'},
-      'u': {'': 'ぬ'},
-      'e': {'': 'ね'},
-      'o': {'': 'の'},
-      'y': {
-        'a': {'': 'にゃ'},
-        'i': {'': 'にぃ'},
-        'u': {'': 'にゅ'},
-        'e': {'': 'にぇ'},
-        'o': {'': 'にょ'}
+        'a': {'': 'っとぁ'},
+        'i': {'': 'っとぃ'},
+        'u': {'': 'っとぅ'},
+        'e': {'': 'っとぇ'},
+        'o': {'': 'っとぉ'},
       },
-      '': 'ん',
-      "'": {'': 'ん'}
+    },
+  },
+  'n': {
+    'a': {'': 'な'},
+    'i': {'': 'に'},
+    'u': {'': 'ぬ'},
+    'e': {'': 'ね'},
+    'o': {'': 'の'},
+    'y': {
+      'a': {'': 'にゃ'},
+      'i': {'': 'にぃ'},
+      'u': {'': 'にゅ'},
+      'e': {'': 'にぇ'},
+      'o': {'': 'にょ'},
+    },
+    '': 'ん',
+    "'": {'': 'ん'},
+  },
+  'h': {
+    'a': {'': 'は'},
+    'i': {'': 'ひ'},
+    'u': {'': 'ふ'},
+    'e': {'': 'へ'},
+    'o': {'': 'ほ'},
+    'y': {
+      'a': {'': 'ひゃ'},
+      'i': {'': 'ひぃ'},
+      'u': {'': 'ひゅ'},
+      'e': {'': 'ひぇ'},
+      'o': {'': 'ひょ'},
     },
     'h': {
-      'a': {'': 'は'},
-      'i': {'': 'ひ'},
-      'u': {'': 'ふ'},
-      'e': {'': 'へ'},
-      'o': {'': 'ほ'},
+      'a': {'': 'っは'},
+      'i': {'': 'っひ'},
+      'u': {'': 'っふ'},
+      'e': {'': 'っへ'},
+      'o': {'': 'っほ'},
       'y': {
-        'a': {'': 'ひゃ'},
-        'i': {'': 'ひぃ'},
-        'u': {'': 'ひゅ'},
-        'e': {'': 'ひぇ'},
-        'o': {'': 'ひょ'}
+        'a': {'': 'っひゃ'},
+        'i': {'': 'っひぃ'},
+        'u': {'': 'っひゅ'},
+        'e': {'': 'っひぇ'},
+        'o': {'': 'っひょ'},
       },
-      'h': {
-        'a': {'': 'っは'},
-        'i': {'': 'っひ'},
-        'u': {'': 'っふ'},
-        'e': {'': 'っへ'},
-        'o': {'': 'っほ'},
-        'y': {
-          'a': {'': 'っひゃ'},
-          'i': {'': 'っひぃ'},
-          'u': {'': 'っひゅ'},
-          'e': {'': 'っひぇ'},
-          'o': {'': 'っひょ'}
-        }
-      }
+    },
+  },
+  'm': {
+    'a': {'': 'ま'},
+    'i': {'': 'み'},
+    'u': {'': 'む'},
+    'e': {'': 'め'},
+    'o': {'': 'も'},
+    'y': {
+      'a': {'': 'みゃ'},
+      'i': {'': 'みぃ'},
+      'u': {'': 'みゅ'},
+      'e': {'': 'みぇ'},
+      'o': {'': 'みょ'},
     },
     'm': {
-      'a': {'': 'ま'},
-      'i': {'': 'み'},
-      'u': {'': 'む'},
-      'e': {'': 'め'},
-      'o': {'': 'も'},
+      'a': {'': 'っま'},
+      'i': {'': 'っみ'},
+      'u': {'': 'っむ'},
+      'e': {'': 'っめ'},
+      'o': {'': 'っも'},
       'y': {
-        'a': {'': 'みゃ'},
-        'i': {'': 'みぃ'},
-        'u': {'': 'みゅ'},
-        'e': {'': 'みぇ'},
-        'o': {'': 'みょ'}
+        'a': {'': 'っみゃ'},
+        'i': {'': 'っみぃ'},
+        'u': {'': 'っみゅ'},
+        'e': {'': 'っみぇ'},
+        'o': {'': 'っみょ'},
       },
-      'm': {
-        'a': {'': 'っま'},
-        'i': {'': 'っみ'},
-        'u': {'': 'っむ'},
-        'e': {'': 'っめ'},
-        'o': {'': 'っも'},
-        'y': {
-          'a': {'': 'っみゃ'},
-          'i': {'': 'っみぃ'},
-          'u': {'': 'っみゅ'},
-          'e': {'': 'っみぇ'},
-          'o': {'': 'っみょ'}
-        }
-      }
     },
+  },
+  'y': {
+    'a': {'': 'や'},
+    'u': {'': 'ゆ'},
+    'o': {'': 'よ'},
+    'i': {'': 'い'},
+    'e': {'': 'いぇ'},
     'y': {
-      'a': {'': 'や'},
-      'u': {'': 'ゆ'},
-      'o': {'': 'よ'},
-      'i': {'': 'い'},
-      'e': {'': 'いぇ'},
-      'y': {
-        'a': {'': 'っや'},
-        'u': {'': 'っゆ'},
-        'o': {'': 'っよ'},
-        'i': {'': 'っい'},
-        'e': {'': 'っいぇ'}
-      }
+      'a': {'': 'っや'},
+      'u': {'': 'っゆ'},
+      'o': {'': 'っよ'},
+      'i': {'': 'っい'},
+      'e': {'': 'っいぇ'},
+    },
+  },
+  'r': {
+    'a': {'': 'ら'},
+    'i': {'': 'り'},
+    'u': {'': 'る'},
+    'e': {'': 'れ'},
+    'o': {'': 'ろ'},
+    'y': {
+      'a': {'': 'りゃ'},
+      'i': {'': 'りぃ'},
+      'u': {'': 'りゅ'},
+      'e': {'': 'りぇ'},
+      'o': {'': 'りょ'},
     },
     'r': {
-      'a': {'': 'ら'},
-      'i': {'': 'り'},
-      'u': {'': 'る'},
-      'e': {'': 'れ'},
-      'o': {'': 'ろ'},
+      'a': {'': 'っら'},
+      'i': {'': 'っり'},
+      'u': {'': 'っる'},
+      'e': {'': 'っれ'},
+      'o': {'': 'っろ'},
       'y': {
-        'a': {'': 'りゃ'},
-        'i': {'': 'りぃ'},
-        'u': {'': 'りゅ'},
-        'e': {'': 'りぇ'},
-        'o': {'': 'りょ'}
+        'a': {'': 'っりゃ'},
+        'i': {'': 'っりぃ'},
+        'u': {'': 'っりゅ'},
+        'e': {'': 'っりぇ'},
+        'o': {'': 'っりょ'},
       },
-      'r': {
-        'a': {'': 'っら'},
-        'i': {'': 'っり'},
-        'u': {'': 'っる'},
-        'e': {'': 'っれ'},
-        'o': {'': 'っろ'},
-        'y': {
-          'a': {'': 'っりゃ'},
-          'i': {'': 'っりぃ'},
-          'u': {'': 'っりゅ'},
-          'e': {'': 'っりぇ'},
-          'o': {'': 'っりょ'}
-        }
-      }
     },
-    'w': {
-      'a': {'': 'わ'},
+  },
+  'w': {
+    'a': {'': 'わ'},
+    'i': {'': 'うぃ'},
+    'e': {'': 'うぇ'},
+    'o': {'': 'を'},
+    'h': {
+      'a': {'': 'うぁ'},
       'i': {'': 'うぃ'},
+      'u': {'': 'う'},
       'e': {'': 'うぇ'},
-      'o': {'': 'を'},
+      'o': {'': 'うぉ'},
+    },
+    'u': {'': 'う'},
+    'w': {
+      'a': {'': 'っわ'},
+      'i': {'': 'っうぃ'},
+      'e': {'': 'っうぇ'},
+      'o': {'': 'っを'},
       'h': {
-        'a': {'': 'うぁ'},
-        'i': {'': 'うぃ'},
-        'u': {'': 'う'},
-        'e': {'': 'うぇ'},
-        'o': {'': 'うぉ'}
-      },
-      'u': {'': 'う'},
-      'w': {
-        'a': {'': 'っわ'},
+        'a': {'': 'っうぁ'},
         'i': {'': 'っうぃ'},
+        'u': {'': 'っう'},
         'e': {'': 'っうぇ'},
-        'o': {'': 'っを'},
-        'h': {
-          'a': {'': 'っうぁ'},
-          'i': {'': 'っうぃ'},
-          'u': {'': 'っう'},
-          'e': {'': 'っうぇ'},
-          'o': {'': 'っうぉ'}
-        },
-        'u': {'': 'っう'}
-      }
+        'o': {'': 'っうぉ'},
+      },
+      'u': {'': 'っう'},
+    },
+  },
+  'g': {
+    'a': {'': 'が'},
+    'i': {'': 'ぎ'},
+    'u': {'': 'ぐ'},
+    'e': {'': 'げ'},
+    'o': {'': 'ご'},
+    'y': {
+      'a': {'': 'ぎゃ'},
+      'i': {'': 'ぎぃ'},
+      'u': {'': 'ぎゅ'},
+      'e': {'': 'ぎぇ'},
+      'o': {'': 'ぎょ'},
+    },
+    'w': {
+      'a': {'': 'ぐぁ'},
+      'i': {'': 'ぐぃ'},
+      'u': {'': 'ぐぅ'},
+      'e': {'': 'ぐぇ'},
+      'o': {'': 'ぐぉ'},
     },
     'g': {
-      'a': {'': 'が'},
-      'i': {'': 'ぎ'},
-      'u': {'': 'ぐ'},
-      'e': {'': 'げ'},
-      'o': {'': 'ご'},
+      'a': {'': 'っが'},
+      'i': {'': 'っぎ'},
+      'u': {'': 'っぐ'},
+      'e': {'': 'っげ'},
+      'o': {'': 'っご'},
       'y': {
-        'a': {'': 'ぎゃ'},
-        'i': {'': 'ぎぃ'},
-        'u': {'': 'ぎゅ'},
-        'e': {'': 'ぎぇ'},
-        'o': {'': 'ぎょ'}
+        'a': {'': 'っぎゃ'},
+        'i': {'': 'っぎぃ'},
+        'u': {'': 'っぎゅ'},
+        'e': {'': 'っぎぇ'},
+        'o': {'': 'っぎょ'},
       },
       'w': {
-        'a': {'': 'ぐぁ'},
-        'i': {'': 'ぐぃ'},
-        'u': {'': 'ぐぅ'},
-        'e': {'': 'ぐぇ'},
-        'o': {'': 'ぐぉ'}
+        'a': {'': 'っぐぁ'},
+        'i': {'': 'っぐぃ'},
+        'u': {'': 'っぐぅ'},
+        'e': {'': 'っぐぇ'},
+        'o': {'': 'っぐぉ'},
       },
-      'g': {
-        'a': {'': 'っが'},
-        'i': {'': 'っぎ'},
-        'u': {'': 'っぐ'},
-        'e': {'': 'っげ'},
-        'o': {'': 'っご'},
-        'y': {
-          'a': {'': 'っぎゃ'},
-          'i': {'': 'っぎぃ'},
-          'u': {'': 'っぎゅ'},
-          'e': {'': 'っぎぇ'},
-          'o': {'': 'っぎょ'}
-        },
-        'w': {
-          'a': {'': 'っぐぁ'},
-          'i': {'': 'っぐぃ'},
-          'u': {'': 'っぐぅ'},
-          'e': {'': 'っぐぇ'},
-          'o': {'': 'っぐぉ'}
-        }
-      }
+    },
+  },
+  'z': {
+    'a': {'': 'ざ'},
+    'i': {'': 'じ'},
+    'u': {'': 'ず'},
+    'e': {'': 'ぜ'},
+    'o': {'': 'ぞ'},
+    'y': {
+      'a': {'': 'じゃ'},
+      'i': {'': 'じぃ'},
+      'u': {'': 'じゅ'},
+      'e': {'': 'じぇ'},
+      'o': {'': 'じょ'},
     },
     'z': {
-      'a': {'': 'ざ'},
-      'i': {'': 'じ'},
-      'u': {'': 'ず'},
-      'e': {'': 'ぜ'},
-      'o': {'': 'ぞ'},
+      'a': {'': 'っざ'},
+      'i': {'': 'っじ'},
+      'u': {'': 'っず'},
+      'e': {'': 'っぜ'},
+      'o': {'': 'っぞ'},
       'y': {
-        'a': {'': 'じゃ'},
-        'i': {'': 'じぃ'},
-        'u': {'': 'じゅ'},
-        'e': {'': 'じぇ'},
-        'o': {'': 'じょ'}
+        'a': {'': 'っじゃ'},
+        'i': {'': 'っじぃ'},
+        'u': {'': 'っじゅ'},
+        'e': {'': 'っじぇ'},
+        'o': {'': 'っじょ'},
       },
-      'z': {
-        'a': {'': 'っざ'},
-        'i': {'': 'っじ'},
-        'u': {'': 'っず'},
-        'e': {'': 'っぜ'},
-        'o': {'': 'っぞ'},
-        'y': {
-          'a': {'': 'っじゃ'},
-          'i': {'': 'っじぃ'},
-          'u': {'': 'っじゅ'},
-          'e': {'': 'っじぇ'},
-          'o': {'': 'っじょ'}
-        }
-      }
+    },
+  },
+  'd': {
+    'a': {'': 'だ'},
+    'i': {'': 'ぢ'},
+    'u': {'': 'づ'},
+    'e': {'': 'で'},
+    'o': {'': 'ど'},
+    'y': {
+      'a': {'': 'ぢゃ'},
+      'i': {'': 'ぢぃ'},
+      'u': {'': 'ぢゅ'},
+      'e': {'': 'ぢぇ'},
+      'o': {'': 'ぢょ'},
+    },
+    'h': {
+      'a': {'': 'でゃ'},
+      'i': {'': 'でぃ'},
+      'u': {'': 'でゅ'},
+      'e': {'': 'でぇ'},
+      'o': {'': 'でょ'},
+    },
+    'w': {
+      'a': {'': 'どぁ'},
+      'i': {'': 'どぃ'},
+      'u': {'': 'どぅ'},
+      'e': {'': 'どぇ'},
+      'o': {'': 'どぉ'},
     },
     'd': {
-      'a': {'': 'だ'},
-      'i': {'': 'ぢ'},
-      'u': {'': 'づ'},
-      'e': {'': 'で'},
-      'o': {'': 'ど'},
+      'a': {'': 'っだ'},
+      'i': {'': 'っぢ'},
+      'u': {'': 'っづ'},
+      'e': {'': 'っで'},
+      'o': {'': 'っど'},
       'y': {
-        'a': {'': 'ぢゃ'},
-        'i': {'': 'ぢぃ'},
-        'u': {'': 'ぢゅ'},
-        'e': {'': 'ぢぇ'},
-        'o': {'': 'ぢょ'}
+        'a': {'': 'っぢゃ'},
+        'i': {'': 'っぢぃ'},
+        'u': {'': 'っぢゅ'},
+        'e': {'': 'っぢぇ'},
+        'o': {'': 'っぢょ'},
       },
       'h': {
-        'a': {'': 'でゃ'},
-        'i': {'': 'でぃ'},
-        'u': {'': 'でゅ'},
-        'e': {'': 'でぇ'},
-        'o': {'': 'でょ'}
+        'a': {'': 'っでゃ'},
+        'i': {'': 'っでぃ'},
+        'u': {'': 'っでゅ'},
+        'e': {'': 'っでぇ'},
+        'o': {'': 'っでょ'},
       },
       'w': {
-        'a': {'': 'どぁ'},
-        'i': {'': 'どぃ'},
-        'u': {'': 'どぅ'},
-        'e': {'': 'どぇ'},
-        'o': {'': 'どぉ'}
+        'a': {'': 'っどぁ'},
+        'i': {'': 'っどぃ'},
+        'u': {'': 'っどぅ'},
+        'e': {'': 'っどぇ'},
+        'o': {'': 'っどぉ'},
       },
-      'd': {
-        'a': {'': 'っだ'},
-        'i': {'': 'っぢ'},
-        'u': {'': 'っづ'},
-        'e': {'': 'っで'},
-        'o': {'': 'っど'},
-        'y': {
-          'a': {'': 'っぢゃ'},
-          'i': {'': 'っぢぃ'},
-          'u': {'': 'っぢゅ'},
-          'e': {'': 'っぢぇ'},
-          'o': {'': 'っぢょ'}
-        },
-        'h': {
-          'a': {'': 'っでゃ'},
-          'i': {'': 'っでぃ'},
-          'u': {'': 'っでゅ'},
-          'e': {'': 'っでぇ'},
-          'o': {'': 'っでょ'}
-        },
-        'w': {
-          'a': {'': 'っどぁ'},
-          'i': {'': 'っどぃ'},
-          'u': {'': 'っどぅ'},
-          'e': {'': 'っどぇ'},
-          'o': {'': 'っどぉ'}
-        }
-      }
+    },
+  },
+  'b': {
+    'a': {'': 'ば'},
+    'i': {'': 'び'},
+    'u': {'': 'ぶ'},
+    'e': {'': 'べ'},
+    'o': {'': 'ぼ'},
+    'y': {
+      'a': {'': 'びゃ'},
+      'i': {'': 'びぃ'},
+      'u': {'': 'びゅ'},
+      'e': {'': 'びぇ'},
+      'o': {'': 'びょ'},
     },
     'b': {
-      'a': {'': 'ば'},
-      'i': {'': 'び'},
-      'u': {'': 'ぶ'},
-      'e': {'': 'べ'},
-      'o': {'': 'ぼ'},
+      'a': {'': 'っば'},
+      'i': {'': 'っび'},
+      'u': {'': 'っぶ'},
+      'e': {'': 'っべ'},
+      'o': {'': 'っぼ'},
       'y': {
-        'a': {'': 'びゃ'},
-        'i': {'': 'びぃ'},
-        'u': {'': 'びゅ'},
-        'e': {'': 'びぇ'},
-        'o': {'': 'びょ'}
+        'a': {'': 'っびゃ'},
+        'i': {'': 'っびぃ'},
+        'u': {'': 'っびゅ'},
+        'e': {'': 'っ���ぇ'},
+        'o': {'': 'っびょ'},
       },
-      'b': {
-        'a': {'': 'っば'},
-        'i': {'': 'っび'},
-        'u': {'': 'っぶ'},
-        'e': {'': 'っべ'},
-        'o': {'': 'っぼ'},
-        'y': {
-          'a': {'': 'っびゃ'},
-          'i': {'': 'っびぃ'},
-          'u': {'': 'っびゅ'},
-          'e': {'': 'っ���ぇ'},
-          'o': {'': 'っびょ'}
-        }
-      }
+    },
+  },
+  'p': {
+    'a': {'': 'ぱ'},
+    'i': {'': 'ぴ'},
+    'u': {'': 'ぷ'},
+    'e': {'': 'ぺ'},
+    'o': {'': 'ぽ'},
+    'y': {
+      'a': {'': 'ぴゃ'},
+      'i': {'': 'ぴぃ'},
+      'u': {'': 'ぴゅ'},
+      'e': {'': 'ぴぇ'},
+      'o': {'': 'ぴょ'},
     },
     'p': {
-      'a': {'': 'ぱ'},
-      'i': {'': 'ぴ'},
-      'u': {'': 'ぷ'},
-      'e': {'': 'ぺ'},
-      'o': {'': 'ぽ'},
+      'a': {'': 'っぱ'},
+      'i': {'': 'っぴ'},
+      'u': {'': 'っぷ'},
+      'e': {'': 'っぺ'},
+      'o': {'': 'っぽ'},
       'y': {
-        'a': {'': 'ぴゃ'},
-        'i': {'': 'ぴぃ'},
-        'u': {'': 'ぴゅ'},
-        'e': {'': 'ぴぇ'},
-        'o': {'': 'ぴょ'}
+        'a': {'': 'っぴゃ'},
+        'i': {'': 'っぴぃ'},
+        'u': {'': 'っぴゅ'},
+        'e': {'': 'っぴぇ'},
+        'o': {'': 'っぴょ'},
       },
-      'p': {
-        'a': {'': 'っぱ'},
-        'i': {'': 'っぴ'},
-        'u': {'': 'っぷ'},
-        'e': {'': 'っぺ'},
-        'o': {'': 'っぽ'},
-        'y': {
-          'a': {'': 'っぴゃ'},
-          'i': {'': 'っぴぃ'},
-          'u': {'': 'っぴゅ'},
-          'e': {'': 'っぴぇ'},
-          'o': {'': 'っぴょ'}
-        }
-      }
     },
-    'v': {
-      'a': {'': 'ゔぁ'},
+  },
+  'v': {
+    'a': {'': 'ゔぁ'},
+    'i': {'': 'ゔぃ'},
+    'u': {'': 'ゔ'},
+    'e': {'': 'ゔぇ'},
+    'o': {'': 'ゔぉ'},
+    'y': {
+      'a': {'': 'ゔゃ'},
       'i': {'': 'ゔぃ'},
-      'u': {'': 'ゔ'},
+      'u': {'': 'ゔゅ'},
       'e': {'': 'ゔぇ'},
-      'o': {'': 'ゔぉ'},
+      'o': {'': 'ゔょ'},
+    },
+    'v': {
+      'a': {'': 'っゔぁ'},
+      'i': {'': 'っゔぃ'},
+      'u': {'': 'っゔ'},
+      'e': {'': 'っゔぇ'},
+      'o': {'': 'っゔぉ'},
       'y': {
-        'a': {'': 'ゔゃ'},
-        'i': {'': 'ゔぃ'},
-        'u': {'': 'ゔゅ'},
-        'e': {'': 'ゔぇ'},
-        'o': {'': 'ゔょ'}
-      },
-      'v': {
-        'a': {'': 'っゔぁ'},
+        'a': {'': 'っゔゃ'},
         'i': {'': 'っゔぃ'},
-        'u': {'': 'っゔ'},
+        'u': {'': 'っゔゅ'},
         'e': {'': 'っゔぇ'},
-        'o': {'': 'っゔぉ'},
-        'y': {
-          'a': {'': 'っゔゃ'},
-          'i': {'': 'っゔぃ'},
-          'u': {'': 'っゔゅ'},
-          'e': {'': 'っゔぇ'},
-          'o': {'': 'っゔょ'}
-        }
-      }
-    },
-    'q': {
-      'y': {
-        'a': {'': 'くゃ'},
-        'i': {'': 'くぃ'},
-        'u': {'': 'くゅ'},
-        'e': {'': 'くぇ'},
-        'o': {'': 'くょ'}
-      },
-      'w': {
-        'a': {'': 'くぁ'},
-        'i': {'': 'くぃ'},
-        'u': {'': 'くぅ'},
-        'e': {'': 'くぇ'},
-        'o': {'': 'くぉ'}
+        'o': {'': 'っゔょ'},
       },
+    },
+  },
+  'q': {
+    'y': {
+      'a': {'': 'くゃ'},
+      'i': {'': 'くぃ'},
+      'u': {'': 'くゅ'},
+      'e': {'': 'くぇ'},
+      'o': {'': 'くょ'},
+    },
+    'w': {
       'a': {'': 'くぁ'},
       'i': {'': 'くぃ'},
       'u': {'': 'くぅ'},
       'e': {'': 'くぇ'},
       'o': {'': 'くぉ'},
-      'q': {
-        'y': {
-          'a': {'': 'っくゃ'},
-          'i': {'': 'っくぃ'},
-          'u': {'': 'っくゅ'},
-          'e': {'': 'っくぇ'},
-          'o': {'': 'っくょ'}
-        },
-        'w': {
-          'a': {'': 'っくぁ'},
-          'i': {'': 'っくぃ'},
-          'u': {'': 'っくぅ'},
-          'e': {'': 'っくぇ'},
-          'o': {'': 'っくぉ'}
-        },
-        'a': {'': 'っくぁ'},
-        'i': {'': 'っくぃ'},
-        'u': {'': 'っくぅ'},
-        'e': {'': 'っくぇ'},
-        'o': {'': 'っくぉ'}
-      }
     },
-    'f': {
+    'a': {'': 'くぁ'},
+    'i': {'': 'くぃ'},
+    'u': {'': 'くぅ'},
+    'e': {'': 'くぇ'},
+    'o': {'': 'くぉ'},
+    'q': {
       'y': {
-        'a': {'': 'ふゃ'},
-        'i': {'': 'ふぃ'},
-        'u': {'': 'ふゅ'},
-        'e': {'': 'ふぇ'},
-        'o': {'': 'ふょ'}
+        'a': {'': 'っくゃ'},
+        'i': {'': 'っくぃ'},
+        'u': {'': 'っくゅ'},
+        'e': {'': 'っくぇ'},
+        'o': {'': 'っくょ'},
       },
       'w': {
-        'a': {'': 'ふぁ'},
-        'i': {'': 'ふぃ'},
-        'u': {'': 'ふぅ'},
-        'e': {'': 'ふぇ'},
-        'o': {'': 'ふぉ'}
+        'a': {'': 'っくぁ'},
+        'i': {'': 'っくぃ'},
+        'u': {'': 'っくぅ'},
+        'e': {'': 'っくぇ'},
+        'o': {'': 'っくぉ'},
       },
+      'a': {'': 'っくぁ'},
+      'i': {'': 'っくぃ'},
+      'u': {'': 'っくぅ'},
+      'e': {'': 'っくぇ'},
+      'o': {'': 'っくぉ'},
+    },
+  },
+  'f': {
+    'y': {
+      'a': {'': 'ふゃ'},
+      'i': {'': 'ふぃ'},
+      'u': {'': 'ふゅ'},
+      'e': {'': 'ふぇ'},
+      'o': {'': 'ふょ'},
+    },
+    'w': {
       'a': {'': 'ふぁ'},
       'i': {'': 'ふぃ'},
-      'u': {'': 'ふ'},
+      'u': {'': 'ふぅ'},
       'e': {'': 'ふぇ'},
       'o': {'': 'ふぉ'},
-      'f': {
-        'y': {
-          'a': {'': 'っふゃ'},
-          'i': {'': 'っふぃ'},
-          'u': {'': 'っふゅ'},
-          'e': {'': 'っふぇ'},
-          'o': {'': 'っふょ'}
-        },
-        'w': {
-          'a': {'': 'っふぁ'},
-          'i': {'': 'っふぃ'},
-          'u': {'': 'っふぅ'},
-          'e': {'': 'っふぇ'},
-          'o': {'': 'っふぉ'}
-        },
-        'a': {'': 'っふぁ'},
+    },
+    'a': {'': 'ふぁ'},
+    'i': {'': 'ふぃ'},
+    'u': {'': 'ふ'},
+    'e': {'': 'ふぇ'},
+    'o': {'': 'ふぉ'},
+    'f': {
+      'y': {
+        'a': {'': 'っふゃ'},
         'i': {'': 'っふぃ'},
-        'u': {'': 'っふ'},
+        'u': {'': 'っふゅ'},
         'e': {'': 'っふぇ'},
-        'o': {'': 'っふぉ'}
-      }
-    },
-    '.': {'': '。'},
-    ',': {'': '、'},
-    ':': {'': '：'},
-    '/': {'': '・'},
-    '!': {'': '！'},
-    '?': {'': '？'},
-    '~': {'': '〜'},
-    '-': {'': 'ー'},
-    '‘': {'': '「'},
-    '’': {'': '」'},
-    '“': {'': '『'},
-    '”': {'': '』'},
-    '[': {'': '［'},
-    ']': {'': '］'},
-    '(': {'': '（'},
-    ')': {'': '）'},
-    '{': {'': '｛'},
-    '}': {'': '｝'},
-    ' ': {'': '　'},
-    'x': {
-      'n': {'': 'ん'},
-      't': {
-        'u': {'': 'っ'},
-        's': {
-          'u': {'': 'っ'}
-        }
+        'o': {'': 'っふょ'},
       },
       'w': {
-        'a': {'': 'ゎ'}
-      },
-      'k': {
-        'a': {'': 'ヵ'},
-        'e': {'': 'ヶ'}
+        'a': {'': 'っふぁ'},
+        'i': {'': 'っふぃ'},
+        'u': {'': 'っふぅ'},
+        'e': {'': 'っふぇ'},
+        'o': {'': 'っふぉ'},
       },
-      'c': {
-        'a': {'': 'ヵ'},
-        'e': {'': 'ヶ'}
+      'a': {'': 'っふぁ'},
+      'i': {'': 'っふぃ'},
+      'u': {'': 'っふ'},
+      'e': {'': 'っふぇ'},
+      'o': {'': 'っふぉ'},
+    },
+  },
+  '.': {'': '。'},
+  ',': {'': '、'},
+  ':': {'': '：'},
+  '/': {'': '・'},
+  '!': {'': '！'},
+  '?': {'': '？'},
+  '~': {'': '〜'},
+  '-': {'': 'ー'},
+  '‘': {'': '「'},
+  '’': {'': '」'},
+  '“': {'': '『'},
+  '”': {'': '』'},
+  '[': {'': '［'},
+  ']': {'': '］'},
+  '(': {'': '（'},
+  ')': {'': '）'},
+  '{': {'': '｛'},
+  '}': {'': '｝'},
+  ' ': {'': '　'},
+  'x': {
+    'n': {'': 'ん'},
+    't': {
+      'u': {'': 'っ'},
+      's': {
+        'u': {'': 'っ'},
       },
-      'a': {'': 'ぁ'},
+    },
+    'w': {
+      'a': {'': 'ゎ'},
+    },
+    'k': {
+      'a': {'': 'ヵ'},
+      'e': {'': 'ヶ'},
+    },
+    'c': {
+      'a': {'': 'ヵ'},
+      'e': {'': 'ヶ'},
+    },
+    'a': {'': 'ぁ'},
+    'i': {'': 'ぃ'},
+    'u': {'': 'ぅ'},
+    'e': {'': 'ぇ'},
+    'o': {'': 'ぉ'},
+    'y': {
+      'a': {'': 'ゃ'},
       'i': {'': 'ぃ'},
-      'u': {'': 'ぅ'},
+      'u': {'': 'ゅ'},
       'e': {'': 'ぇ'},
-      'o': {'': 'ぉ'},
-      'y': {
-        'a': {'': 'ゃ'},
-        'i': {'': 'ぃ'},
-        'u': {'': 'ゅ'},
-        'e': {'': 'ぇ'},
-        'o': {'': 'ょ'}
-      }
+      'o': {'': 'ょ'},
     },
-    'c': {
-      'a': {'': 'か'},
-      'i': {'': 'き'},
-      'u': {'': 'く'},
-      'e': {'': 'け'},
-      'o': {'': 'こ'},
+  },
+  'c': {
+    'a': {'': 'か'},
+    'i': {'': 'き'},
+    'u': {'': 'く'},
+    'e': {'': 'け'},
+    'o': {'': 'こ'},
+    'y': {
+      'a': {'': 'ちゃ'},
+      'i': {'': 'ちぃ'},
+      'u': {'': 'ちゅ'},
+      'e': {'': 'ちぇ'},
+      'o': {'': 'ちょ'},
+    },
+    'h': {
+      'a': {'': 'ちゃ'},
+      'i': {'': 'ち'},
+      'u': {'': 'ちゅ'},
+      'e': {'': 'ちぇ'},
+      'o': {'': 'ちょ'},
       'y': {
         'a': {'': 'ちゃ'},
         'i': {'': 'ちぃ'},
         'u': {'': 'ちゅ'},
         'e': {'': 'ちぇ'},
-        'o': {'': 'ちょ'}
-      },
-      'h': {
-        'a': {'': 'ちゃ'},
-        'i': {'': 'ち'},
-        'u': {'': 'ちゅ'},
-        'e': {'': 'ちぇ'},
         'o': {'': 'ちょ'},
-        'y': {
-          'a': {'': 'ちゃ'},
-          'i': {'': 'ちぃ'},
-          'u': {'': 'ちゅ'},
-          'e': {'': 'ちぇ'},
-          'o': {'': 'ちょ'}
-        }
       },
-      'c': {
-        'a': {'': 'っか'},
-        'i': {'': 'っき'},
-        'u': {'': 'っく'},
-        'e': {'': 'っけ'},
-        'o': {'': 'っこ'},
+    },
+    'c': {
+      'a': {'': 'っか'},
+      'i': {'': 'っき'},
+      'u': {'': 'っく'},
+      'e': {'': 'っけ'},
+      'o': {'': 'っこ'},
+      'y': {
+        'a': {'': 'っちゃ'},
+        'i': {'': 'っちぃ'},
+        'u': {'': 'っちゅ'},
+        'e': {'': 'っちぇ'},
+        'o': {'': 'っちょ'},
+      },
+      'h': {
+        'a': {'': 'っちゃ'},
+        'i': {'': 'っち'},
+        'u': {'': 'っちゅ'},
+        'e': {'': 'っちぇ'},
+        'o': {'': 'っちょ'},
         'y': {
           'a': {'': 'っちゃ'},
           'i': {'': 'っちぃ'},
           'u': {'': 'っちゅ'},
           'e': {'': 'っちぇ'},
-          'o': {'': 'っちょ'}
-        },
-        'h': {
-          'a': {'': 'っちゃ'},
-          'i': {'': 'っち'},
-          'u': {'': 'っちゅ'},
-          'e': {'': 'っちぇ'},
           'o': {'': 'っちょ'},
-          'y': {
-            'a': {'': 'っちゃ'},
-            'i': {'': 'っちぃ'},
-            'u': {'': 'っちゅ'},
-            'e': {'': 'っちぇ'},
-            'o': {'': 'っちょ'}
-          }
-        }
-      }
+        },
+      },
     },
-    'j': {
+  },
+  'j': {
+    'a': {'': 'じゃ'},
+    'i': {'': 'じ'},
+    'u': {'': 'じゅ'},
+    'e': {'': 'じぇ'},
+    'o': {'': 'じょ'},
+    'y': {
       'a': {'': 'じゃ'},
-      'i': {'': 'じ'},
+      'i': {'': 'じぃ'},
       'u': {'': 'じゅ'},
       'e': {'': 'じぇ'},
       'o': {'': 'じょ'},
+    },
+    'j': {
+      'a': {'': 'っじゃ'},
+      'i': {'': 'っじ'},
+      'u': {'': 'っじゅ'},
+      'e': {'': 'っじぇ'},
+      'o': {'': 'っじょ'},
       'y': {
-        'a': {'': 'じゃ'},
-        'i': {'': 'じぃ'},
-        'u': {'': 'じゅ'},
-        'e': {'': 'じぇ'},
-        'o': {'': 'じょ'}
-      },
-      'j': {
         'a': {'': 'っじゃ'},
-        'i': {'': 'っじ'},
+        'i': {'': 'っじぃ'},
         'u': {'': 'っじゅ'},
         'e': {'': 'っじぇ'},
         'o': {'': 'っじょ'},
-        'y': {
-          'a': {'': 'っじゃ'},
-          'i': {'': 'っじぃ'},
-          'u': {'': 'っじゅ'},
-          'e': {'': 'っじぇ'},
-          'o': {'': 'っじょ'}
-        }
-      }
-    },
-    'l': {
-      't': {
-        'u': {'': 'っ'},
-        's': {
-          'u': {'': 'っ'}
-        }
       },
-      'w': {
-        'a': {'': 'ゎ'}
-      },
-      'k': {
-        'a': {'': 'ヵ'},
-        'e': {'': 'ヶ'}
-      },
-      'c': {
-        'a': {'': 'ヵ'},
-        'e': {'': 'ヶ'}
+    },
+  },
+  'l': {
+    't': {
+      'u': {'': 'っ'},
+      's': {
+        'u': {'': 'っ'},
       },
-      'a': {'': 'ぁ'},
+    },
+    'w': {
+      'a': {'': 'ゎ'},
+    },
+    'k': {
+      'a': {'': 'ヵ'},
+      'e': {'': 'ヶ'},
+    },
+    'c': {
+      'a': {'': 'ヵ'},
+      'e': {'': 'ヶ'},
+    },
+    'a': {'': 'ぁ'},
+    'i': {'': 'ぃ'},
+    'u': {'': 'ぅ'},
+    'e': {'': 'ぇ'},
+    'o': {'': 'ぉ'},
+    'y': {
+      'a': {'': 'ゃ'},
       'i': {'': 'ぃ'},
-      'u': {'': 'ぅ'},
+      'u': {'': 'ゅ'},
       'e': {'': 'ぇ'},
-      'o': {'': 'ぉ'},
-      'y': {
-        'a': {'': 'ゃ'},
-        'i': {'': 'ぃ'},
-        'u': {'': 'ゅ'},
-        'e': {'': 'ぇ'},
-        'o': {'': 'ょ'}
-      }
-    }
+      'o': {'': 'ょ'},
+    },
   },
-);
+};
diff --git a/lib/src/models/romanization/romanization.dart b/lib/src/models/romanization/romanization.dart
index 006ae18..f81b7fc 100644
--- a/lib/src/models/romanization/romanization.dart
+++ b/lib/src/models/romanization/romanization.dart
@@ -1,14 +1,20 @@
-import 'package:equatable/equatable.dart';
-
 part 'hepburn.dart';
 
-/// A class containing maps that indicates how to convert between kana
+/// An enum containing maps that indicates how to convert between kana
 /// characters and romaji.
 ///
-/// Currently only supports [hepburn]
+/// Currently only supports [hepburn].
 /// (https://en.wikipedia.org/wiki/Hepburn_romanization).
-class Romanization extends Equatable {
-  const Romanization._({
+enum Romanization {
+  /// The Hepburn romanization map. (https://en.wikipedia.org/wiki/Hepburn_romanization)
+  hepburn(
+    name: 'Hepburn',
+    kanaToRomajiMap: _hepburnKanaToRomajiMap,
+    romajiToKanaMap: _hepburnRomajiToKanaMap,
+  ),
+  ;
+
+  const Romanization({
     required this.name,
     required this.kanaToRomajiMap,
     required this.romajiToKanaMap,
@@ -23,15 +29,6 @@ class Romanization extends Equatable {
   /// The map that can be used to convert from romaji to kana.
   final Map<String, dynamic> romajiToKanaMap;
 
-  /// The Hepburn romanization map. (https://en.wikipedia.org/wiki/Hepburn_romanization)
-  static const hepburn = _hepburn;
-
-  /// Indicates if this is [Romanization.hepburn].
-  bool get isHepburn => this == hepburn;
-
-  @override
-  String toString() => '$Romanization ($name)';
-
   @override
-  List<Object> get props => [name];
+  String toString() => '$Romanization($name)';
 }
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
index dd9d848..c149e6f 100644
--- a/lib/src/utils.dart
+++ b/lib/src/utils.dart
@@ -1,50 +1,33 @@
-import 'package:equatable/equatable.dart';
+import 'dart:core';
 
-/// {@template tuple}
-/// A data class that contains two elements ([left] and [right]).
-/// {@endtemplate}
-class Tuple<T1, T2> extends Equatable {
-  /// {@macro tuple}
-  const Tuple(this.left, this.right);
-
-  /// The first element.
-  final T1 left;
-
-  /// The second element.
-  final T2 right;
-
-  @override
-  bool get stringify => true;
-
-  @override
-  List<Object?> get props => [left, right];
-}
-
-/// Extensions that make handling collections of [Tuple]s more convenient.
-extension TupleIterableUtils<T1, T2> on Iterable<Tuple<T1, T2>> {
+/// Extensions that make handling collections of tuple records more convenient.
+extension TupleRecordIterableExtensions<T1, T2> on Iterable<(T1, T2)> {
   /// Returns a new [Iterator<T1>] that contains all `left` elements.
-  Iterable<T1> get allLefts => map((t) => t.left);
+  Iterable<T1> get allLefts => map((t) => t.$1);
 
   /// Returns a new [Iterator<T2>] that contains all `right` elements.
-  Iterable<T2> get allRights => map((t) => t.right);
+  Iterable<T2> get allRights => map((t) => t.$2);
 }
 
 /// Extensions that make handling [String]s more convenient.
-extension StringUtils on String {
+extension StringExtensions on String {
   /// Returns a list of every character in this `String`.
   List<String> get chars => split('');
 
   /// Returns the reverse of this string.
   ///
+  // cspell: disable
   /// ```dart
   /// "Hello".reversed; // "olleH"
   /// ```
+  // cspell: enable
   String get reversed => chars.reversed.join();
 
   /// The code unit for the first character in this `String`.
   ///
   /// Shorthand for [codeUnitAt(0)].
   int get code {
+    assert(length == 1, 'String must be exactly one character long.');
     return codeUnitAt(0);
   }
 
diff --git a/pubspec.lock b/pubspec.lock
index ceb69eb..2a8db91 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -5,386 +5,401 @@ packages:
     dependency: transitive
     description:
       name: _fe_analyzer_shared
-      url: "https://pub.dartlang.org"
+      sha256: "0b2f2bd91ba804e53a61d757b986f89f1f9eaed5b11e4b2f5a2468d86d6c9fc7"
+      url: "https://pub.dev"
     source: hosted
-    version: "6.0.0"
+    version: "67.0.0"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
-      url: "https://pub.dartlang.org"
+      sha256: "37577842a27e4338429a1cbc32679d508836510b056f1eedf0c8d20e39c1383d"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.39.14"
+    version: "6.4.1"
   args:
     dependency: transitive
     description:
       name: args
-      url: "https://pub.dartlang.org"
+      sha256: "7cf60b9f0cc88203c5a190b4cd62a99feea42759a7fa695010eb5de1c0b2252a"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.6.0"
+    version: "2.5.0"
   async:
     dependency: transitive
     description:
       name: async
-      url: "https://pub.dartlang.org"
+      sha256: "947bfcf187f74dbc5e146c9eb9c0f10c9f8b30743e341481c1e2ed3ecc18c20c"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.5.0"
+    version: "2.11.0"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
-      url: "https://pub.dartlang.org"
+      sha256: "5bbf32bc9e518d41ec49718e2931cd4527292c9b0c6d2dffcf7fe6b9a8a8cf72"
+      url: "https://pub.dev"
     source: hosted
     version: "2.1.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
-      url: "https://pub.dartlang.org"
+      sha256: "8e36feea6de5ea69f2199f29cf42a450a855738c498b57c0b980e2d3cca9c362"
+      url: "https://pub.dev"
     source: hosted
     version: "1.2.0"
-  cli_util:
-    dependency: transitive
+  checks:
+    dependency: "direct main"
     description:
-      name: cli_util
-      url: "https://pub.dartlang.org"
+      name: checks
+      sha256: aad431b45a8ae2fa26db8c22e385b9cdec73f72986a1d9d9f2017f4c39ecf5c9
+      url: "https://pub.dev"
     source: hosted
-    version: "0.1.4"
+    version: "0.3.0"
   collection:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: collection
-      url: "https://pub.dartlang.org"
+      sha256: a1ace0a119f20aabc852d165077c036cd864315bd99b7eaa10a60100341941bf
+      url: "https://pub.dev"
     source: hosted
-    version: "1.15.0"
+    version: "1.19.0"
   convert:
     dependency: transitive
     description:
       name: convert
-      url: "https://pub.dartlang.org"
+      sha256: "0f08b14755d163f6e2134cb58222dd25ea2a2ee8a195e53983d57c075324d592"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.1.1"
+    version: "3.1.1"
   coverage:
-    dependency: transitive
+    dependency: "direct dev"
     description:
       name: coverage
-      url: "https://pub.dartlang.org"
+      sha256: c1fb2dce3c0085f39dc72668e85f8e0210ec7de05345821ff58530567df345a5
+      url: "https://pub.dev"
     source: hosted
-    version: "0.14.2"
+    version: "1.9.2"
   crypto:
     dependency: transitive
     description:
       name: crypto
-      url: "https://pub.dartlang.org"
+      sha256: ec30d999af904f33454ba22ed9a86162b35e52b44ac4807d1d93c288041d7d27
+      url: "https://pub.dev"
     source: hosted
-    version: "2.1.5"
-  csslib:
+    version: "3.0.5"
+  file:
     dependency: transitive
     description:
-      name: csslib
-      url: "https://pub.dartlang.org"
+      name: file
+      sha256: "1b92bec4fc2a72f59a8e15af5f52cd441e4a7860b49499d69dfa817af20e925d"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.16.1"
-  equatable:
-    dependency: "direct main"
+    version: "6.1.4"
+  frontend_server_client:
+    dependency: transitive
     description:
-      name: equatable
-      url: "https://pub.dartlang.org"
+      name: frontend_server_client
+      sha256: f64a0333a82f30b0cca061bc3d143813a486dc086b574bfb233b7c1372427694
+      url: "https://pub.dev"
     source: hosted
-    version: "2.0.0"
+    version: "4.0.0"
   glob:
     dependency: transitive
     description:
       name: glob
-      url: "https://pub.dartlang.org"
+      sha256: "0e7014b3b7d4dac1ca4d6114f82bf1782ee86745b9b42a92c9289c23d8a0ab63"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.2.0"
-  html:
-    dependency: transitive
-    description:
-      name: html
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.14.0+3"
+    version: "2.1.2"
   http_multi_server:
     dependency: transitive
     description:
       name: http_multi_server
-      url: "https://pub.dartlang.org"
+      sha256: "97486f20f9c2f7be8f514851703d0119c3596d14ea63227af6f7a481ef2b2f8b"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.2.0"
+    version: "3.2.1"
   http_parser:
     dependency: transitive
     description:
       name: http_parser
-      url: "https://pub.dartlang.org"
+      sha256: "40f592dd352890c3b60fec1b68e786cefb9603e05ff303dbc4dda49b304ecdf4"
+      url: "https://pub.dev"
     source: hosted
-    version: "3.1.4"
+    version: "4.1.0"
   io:
     dependency: transitive
     description:
       name: io
-      url: "https://pub.dartlang.org"
+      sha256: "2ec25704aba361659e10e3e5f5d672068d332fc8ac516421d483a11e5cbd061e"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.3.4"
+    version: "1.0.4"
   js:
     dependency: transitive
     description:
       name: js
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.6.3"
-  json_annotation:
-    dependency: transitive
-    description:
-      name: json_annotation
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "3.0.1"
-  lcov:
-    dependency: transitive
-    description:
-      name: lcov
-      url: "https://pub.dartlang.org"
+      sha256: c1b2e9b5ea78c45e1a0788d29606ba27dc5f71f019f32ca5140f61ef071838cf
+      url: "https://pub.dev"
     source: hosted
-    version: "5.7.0"
+    version: "0.7.1"
   logging:
     dependency: transitive
     description:
       name: logging
-      url: "https://pub.dartlang.org"
+      sha256: "623a88c9594aa774443aa3eb2d41807a48486b5613e67599fb4c41c0ad47c340"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.11.4"
+    version: "1.2.0"
   matcher:
     dependency: transitive
     description:
       name: matcher
-      url: "https://pub.dartlang.org"
+      sha256: d2323aa2060500f906aa31a895b4030b6da3ebdcc5619d14ce1aada65cd161cb
+      url: "https://pub.dev"
     source: hosted
-    version: "0.12.10"
+    version: "0.12.16+1"
   meta:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: meta
-      url: "https://pub.dartlang.org"
+      sha256: e3641ec5d63ebf0d9b41bd43201a66e3fc79a65db5f61fc181f04cd27aab950c
+      url: "https://pub.dev"
     source: hosted
-    version: "1.3.0"
+    version: "1.16.0"
   mime:
     dependency: transitive
     description:
       name: mime
-      url: "https://pub.dartlang.org"
+      sha256: "801fd0b26f14a4a58ccb09d5892c3fbdeff209594300a542492cf13fba9d247a"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.9.6+3"
-  node_interop:
-    dependency: transitive
-    description:
-      name: node_interop
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.1.1"
-  node_io:
-    dependency: transitive
-    description:
-      name: node_io
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.1.1"
+    version: "1.0.6"
   node_preamble:
     dependency: transitive
     description:
       name: node_preamble
-      url: "https://pub.dartlang.org"
+      sha256: "6e7eac89047ab8a8d26cf16127b5ed26de65209847630400f9aefd7cd5c730db"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.4.12"
+    version: "2.0.2"
   package_config:
     dependency: transitive
     description:
       name: package_config
-      url: "https://pub.dartlang.org"
+      sha256: "1c5b77ccc91e4823a5af61ee74e6b972db1ef98c2ff5a18d3161c982a55448bd"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.9.3"
+    version: "2.1.0"
   path:
     dependency: transitive
     description:
       name: path
-      url: "https://pub.dartlang.org"
+      sha256: "2ad4cddff7f5cc0e2d13069f2a3f7a73ca18f66abd6f5ecf215219cdb3638edb"
+      url: "https://pub.dev"
     source: hosted
     version: "1.8.0"
-  pedantic:
-    dependency: transitive
-    description:
-      name: pedantic
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.11.0"
   pool:
     dependency: transitive
     description:
       name: pool
-      url: "https://pub.dartlang.org"
+      sha256: "05955e3de2683e1746222efd14b775df7131139e07695dc8e24650f6b4204504"
+      url: "https://pub.dev"
     source: hosted
     version: "1.5.0"
   pub_semver:
     dependency: transitive
     description:
       name: pub_semver
-      url: "https://pub.dartlang.org"
+      sha256: "40d3ab1bbd474c4c2328c91e3a7df8c6dd629b79ece4c4bd04bee496a224fb0c"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.4.4"
+    version: "2.1.4"
   shelf:
     dependency: transitive
     description:
       name: shelf
-      url: "https://pub.dartlang.org"
+      sha256: e7dd780a7ffb623c57850b33f43309312fc863fb6aa3d276a754bb299839ef12
+      url: "https://pub.dev"
     source: hosted
-    version: "0.7.7"
+    version: "1.4.2"
   shelf_packages_handler:
     dependency: transitive
     description:
       name: shelf_packages_handler
-      url: "https://pub.dartlang.org"
+      sha256: "89f967eca29607c933ba9571d838be31d67f53f6e4ee15147d5dc2934fee1b1e"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.0.0"
+    version: "3.0.2"
   shelf_static:
     dependency: transitive
     description:
       name: shelf_static
-      url: "https://pub.dartlang.org"
+      sha256: c87c3875f91262785dade62d135760c2c69cb217ac759485334c5857ad89f6e3
+      url: "https://pub.dev"
     source: hosted
-    version: "0.2.8"
+    version: "1.1.3"
   shelf_web_socket:
     dependency: transitive
     description:
       name: shelf_web_socket
-      url: "https://pub.dartlang.org"
+      sha256: "073c147238594ecd0d193f3456a5fe91c4b0abbcc68bf5cd95b36c4e194ac611"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.2.3"
+    version: "2.0.0"
   source_map_stack_trace:
     dependency: transitive
     description:
       name: source_map_stack_trace
-      url: "https://pub.dartlang.org"
+      sha256: "8c463326277f68a628abab20580047b419c2ff66756fd0affd451f73f9508c11"
+      url: "https://pub.dev"
     source: hosted
     version: "2.1.0"
   source_maps:
     dependency: transitive
     description:
       name: source_maps
-      url: "https://pub.dartlang.org"
+      sha256: "52de2200bb098de739794c82d09c41ac27b2e42fd7e23cce7b9c74bf653c7296"
+      url: "https://pub.dev"
     source: hosted
     version: "0.10.10"
   source_span:
     dependency: transitive
     description:
       name: source_span
-      url: "https://pub.dartlang.org"
+      sha256: d5f89a9e52b36240a80282b3dc0667dd36e53459717bb17b8fb102d30496606a
+      url: "https://pub.dev"
     source: hosted
     version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
-      url: "https://pub.dartlang.org"
+      sha256: f8d9f247e2f9f90e32d1495ff32dac7e4ae34ffa7194c5ff8fcc0fd0e52df774
+      url: "https://pub.dev"
     source: hosted
     version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      url: "https://pub.dartlang.org"
+      sha256: db47e4797198ee601990820437179bb90219f918962318d494ada2b4b11e6f6d
+      url: "https://pub.dev"
     source: hosted
     version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
-      url: "https://pub.dartlang.org"
+      sha256: dd11571b8a03f7cadcf91ec26a77e02bfbd6bbba2a512924d3116646b4198fc4
+      url: "https://pub.dev"
     source: hosted
     version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
-      url: "https://pub.dartlang.org"
+      sha256: a88162591b02c1f3a3db3af8ce1ea2b374bd75a7bb8d5e353bcfbdc79d719830
+      url: "https://pub.dev"
     source: hosted
     version: "1.2.0"
   test:
     dependency: "direct dev"
     description:
       name: test
-      url: "https://pub.dartlang.org"
+      sha256: "713a8789d62f3233c46b4a90b174737b2c04cb6ae4500f2aa8b1be8f03f5e67f"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.16.5"
+    version: "1.25.8"
   test_api:
     dependency: transitive
     description:
       name: test_api
-      url: "https://pub.dartlang.org"
+      sha256: "664d3a9a64782fcdeb83ce9c6b39e78fd2971d4e37827b9b06c3aa1edc5e760c"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.2.19"
+    version: "0.7.3"
   test_core:
     dependency: transitive
     description:
       name: test_core
-      url: "https://pub.dartlang.org"
+      sha256: "12391302411737c176b0b5d6491f466b0dd56d4763e347b6714efbaa74d7953d"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.3.15"
-  test_coverage:
-    dependency: "direct dev"
-    description:
-      name: test_coverage
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.5.0"
+    version: "0.6.5"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
-      url: "https://pub.dartlang.org"
+      sha256: "53bdf7e979cfbf3e28987552fd72f637e63f3c8724c9e56d9246942dc2fa36ee"
+      url: "https://pub.dev"
     source: hosted
     version: "1.3.0"
   very_good_analysis:
     dependency: "direct dev"
     description:
       name: very_good_analysis
-      url: "https://pub.dartlang.org"
+      sha256: "1fb637c0022034b1f19ea2acb42a3603cbd8314a470646a59a2fb01f5f3a8629"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.0.4"
+    version: "6.0.0"
   vm_service:
     dependency: transitive
     description:
       name: vm_service
-      url: "https://pub.dartlang.org"
+      sha256: "5c5f338a667b4c644744b661f309fb8080bb94b18a7e91ef1dbd343bed00ed6d"
+      url: "https://pub.dev"
     source: hosted
-    version: "4.1.0"
+    version: "14.2.5"
   watcher:
     dependency: transitive
     description:
       name: watcher
-      url: "https://pub.dartlang.org"
+      sha256: "3d2ad6751b3c16cf07c7fca317a1413b3f26530319181b37e3b9039b84fc01d8"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
+  web:
+    dependency: transitive
+    description:
+      name: web
+      sha256: d43c1d6b787bf0afad444700ae7f4db8827f701bc61c255ac8d328c6f4d52062
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
+  web_socket:
+    dependency: transitive
+    description:
+      name: web_socket
+      sha256: "3c12d96c0c9a4eec095246debcea7b86c0324f22df69893d538fcc6f1b8cce83"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.9.7+15"
+    version: "0.1.6"
   web_socket_channel:
     dependency: transitive
     description:
       name: web_socket_channel
-      url: "https://pub.dartlang.org"
+      sha256: "9f187088ed104edd8662ca07af4b124465893caf063ba29758f97af57e61da8f"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.1.0"
+    version: "3.0.1"
   webkit_inspection_protocol:
     dependency: transitive
     description:
       name: webkit_inspection_protocol
-      url: "https://pub.dartlang.org"
+      sha256: "87d3f2333bb240704cd3f1c6b5b7acd8a10e7f0bc28c28dcf14e782014f4a572"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.7.3"
+    version: "1.2.1"
   yaml:
     dependency: transitive
     description:
       name: yaml
-      url: "https://pub.dartlang.org"
+      sha256: "75769501ea3489fca56601ff33454fe45507ea3bfb014161abc3b43ae25989d5"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.2.1"
+    version: "3.1.2"
 sdks:
-  dart: ">=2.12.0 <3.0.0"
+  dart: ">=3.4.0 <4.0.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index 6765848..0d85aaa 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -2,16 +2,18 @@ name: kana_kit
 description: >
   A Dart library for for detecting and transliterating Hiragana, Katakana, and
   Romaji.
-version: 2.0.0
+version: 2.1.0
 repository: https://github.com/jeroen-meijer/kana_kit
 
 environment:
-  sdk: ">=2.12.0 <3.0.0"
+  sdk: '>=3.0.0 <4.0.0'
 
 dependencies:
-  equatable: ^2.0.0
+  checks: ^0.3.0
+  collection: ^1.19.0
+  meta: ^1.16.0
 
 dev_dependencies:
-  test: 1.16.5
-  test_coverage: 0.5.0
-  very_good_analysis: 1.0.4
+  coverage: 1.9.2
+  test: 1.25.8
+  very_good_analysis: 6.0.0
diff --git a/test/checks_test.dart b/test/checks_test.dart
index 31b4331..c09b48d 100644
--- a/test/checks_test.dart
+++ b/test/checks_test.dart
@@ -1,3 +1,6 @@
+// cspell: disable
+
+import 'package:checks/checks.dart';
 import 'package:kana_kit/kana_kit.dart';
 import 'package:test/test.dart';
 
@@ -15,7 +18,12 @@ CheckerTest checkerTest(Checker checker, String checkResultName) {
     return test(
       '${formatInput(input)} is ${!shouldPass ? 'NOT ' : ''}$checkResultName',
       () {
-        expect(checker(input), shouldPass ? isTrue : isFalse);
+        final testCheck = check(checker(input));
+        if (shouldPass) {
+          testCheck.isTrue();
+        } else {
+          testCheck.isFalse();
+        }
       },
     );
   };
@@ -55,6 +63,7 @@ void main() {
       the(input: 'a！b&cーd', shouldPass: false);
       the(input: 'ｈｅｌｌｏ', shouldPass: false);
     });
+
     group('isJapanese', () {
       final throwsAssertionErrorWithInputIs =
           checkerAssertionTest(kanaKit.isJapanese);
@@ -96,6 +105,7 @@ void main() {
         shouldPass: true,
       );
     });
+
     group('isKana', () {
       final throwsAssertionErrorWithInputIs =
           checkerAssertionTest(kanaKit.isKana);
@@ -109,6 +119,7 @@ void main() {
       the(input: 'あAア', shouldPass: false);
       the(input: 'アーあ', shouldPass: true);
     });
+
     group('isHiragana', () {
       final throwsAssertionErrorWithInputIs =
           checkerAssertionTest(kanaKit.isHiragana);
@@ -122,6 +133,7 @@ void main() {
       the(input: 'あア', shouldPass: false);
       the(input: 'げーむ', shouldPass: true);
     });
+
     group('isKatakana', () {
       final throwsAssertionErrorWithInputIs =
           checkerAssertionTest(kanaKit.isKatakana);
@@ -155,6 +167,7 @@ void main() {
       the(input: '隻。', shouldPass: false);
       the(input: '🐸', shouldPass: false);
     });
+
     group('isMixed', () {
       final throwsAssertionErrorWithInputIs =
           checkerAssertionTest(kanaKit.isMixed);
@@ -176,6 +189,7 @@ void main() {
         the(input: 'あ', shouldPass: false);
         the(input: 'ア', shouldPass: false);
       });
+
       group('(passKanji: false)', () {
         final the = checkerTest(
           kanaKit.copyWithConfig(passKanji: false).isMixed,
diff --git a/test/conversions_test.dart b/test/conversions_test.dart
index 53feaa4..cb96f21 100644
--- a/test/conversions_test.dart
+++ b/test/conversions_test.dart
@@ -1,3 +1,6 @@
+// cspell: disable
+
+import 'package:checks/checks.dart';
 import 'package:kana_kit/kana_kit.dart';
 import 'package:test/test.dart';
 
@@ -13,28 +16,27 @@ typedef ConverterAssertionTest = void Function(String input);
 
 ConverterTest converterTest(Converter converter) {
   return ({required input, shouldBecome, shouldNotBecome}) {
-    if (shouldNotBecome != null) {
-      final shouldChange = input == shouldNotBecome;
-      return test(
-        shouldChange
-            ? '${formatInput(input)} should change'
-            : '${formatInput(input)} does NOT become '
-                '${formatInput(shouldNotBecome)}',
-        () {
-          expect(converter(input), isNot(shouldBecome));
-        },
-      );
-    } else {
-      final shouldNotChange = input == shouldBecome;
-      return test(
-        shouldNotChange
-            ? '${formatInput(input)} should return the same'
-            : '${formatInput(input)} becomes ${formatInput(shouldBecome)}',
-        () {
-          expect(converter(input), shouldBecome);
-        },
-      );
-    }
+    return switch ((shouldBecome, shouldNotBecome)) {
+      (final shouldBecome, _) when shouldBecome != null => test(
+          input == shouldBecome
+              ? '${formatInput(input)} should return the same'
+              : '${formatInput(input)} becomes ${formatInput(shouldBecome)}',
+          () {
+            check(converter(input)).equals(shouldBecome);
+          },
+        ),
+      (_, final shouldNotBecome) when shouldNotBecome != null => test(
+          input == shouldNotBecome
+              ? '${formatInput(input)} should change'
+              : '${formatInput(input)} does NOT become '
+                  '${formatInput(shouldNotBecome)}',
+          () {
+            check(converter(input)).not((it) => it.equals(shouldNotBecome));
+          },
+        ),
+      _ =>
+        throw ArgumentError('shouldBecome or shouldNotBecome must be provided'),
+    };
   };
 }
 
@@ -43,10 +45,7 @@ ConverterAssertionTest converterAssertionTest(Converter checker) {
     return test(
       'throws AssertionError when input is ${formatInput(input)}',
       () {
-        expect(
-          () => checker(input),
-          throwsA(isA<AssertionError>()),
-        );
+        check(() => checker(input)).throws<AssertionError>();
       },
     );
   };
@@ -60,6 +59,7 @@ void main() {
         final the = converterTest(
           kanaKit.copyWithConfig(upcaseKatakana: false).toRomaji,
         );
+
         the(input: '', shouldBecome: '');
         the(input: '.', shouldBecome: '.');
         the(input: 'hello', shouldBecome: 'hello');
@@ -97,11 +97,19 @@ void main() {
           the(input: 'んよ んあ んゆ', shouldBecome: "n'yo n'a n'yu");
           the(input: 'シンヨ', shouldBecome: "shin'yo");
         });
+
+        group('edge cases containing "ゎー" or "ヮー"', () {
+          the(input: 'しーくゎーさー', shouldBecome: 'shiikuwaasaa');
+          the(input: 'しまうゎー', shouldBecome: 'shimauwaa');
+          the(input: 'シークヮーサー', shouldBecome: 'shiikuwaasaa');
+          the(input: 'シマウヮー', shouldBecome: 'shimauwaa');
+        });
       });
       group('(upcaseKatakana: true)', () {
         final the = converterTest(
           kanaKit.copyWithConfig(upcaseKatakana: true).toRomaji,
         );
+
         the(input: '', shouldBecome: '');
         the(input: '.', shouldBecome: '.');
         the(input: 'hello', shouldBecome: 'hello');
@@ -143,6 +151,7 @@ void main() {
     });
     group('toKana', () {
       final the = converterTest(kanaKit.toKana);
+
       the(input: '', shouldBecome: '');
       the(input: '.', shouldBecome: '。');
       the(input: 'onaji', shouldBecome: 'おなじ');
@@ -162,8 +171,8 @@ void main() {
       the(input: 'wi', shouldBecome: 'うぃ');
       the(input: 'WI', shouldBecome: 'ウィ');
       the(
-        input: 'ワニカニ AiUeO 鰐蟹 12345 @#\$%',
-        shouldBecome: 'ワニカニ　アいウえオ　鰐蟹　12345　@#\$%',
+        input: r'ワニカニ AiUeO 鰐蟹 12345 @#$%',
+        shouldBecome: r'ワニカニ　アいウえオ　鰐蟹　12345　@#$%',
       );
     });
 
@@ -172,6 +181,7 @@ void main() {
         final the = converterTest(
           kanaKit.copyWithConfig(passRomaji: false).toHiragana,
         );
+
         the(input: '', shouldBecome: '');
         the(input: '.', shouldBecome: '。');
         the(input: 'wi', shouldBecome: 'うぃ');
@@ -214,6 +224,7 @@ void main() {
         final the = converterTest(
           kanaKit.copyWithConfig(passRomaji: false).toKatakana,
         );
+
         the(input: '', shouldBecome: '');
         the(input: 'ー', shouldBecome: 'ー');
         the(input: '.', shouldBecome: '。');
diff --git a/test/models/kana_kit_config_test.dart b/test/models/kana_kit_config_test.dart
index 7b50d1d..d8a6abd 100644
--- a/test/models/kana_kit_config_test.dart
+++ b/test/models/kana_kit_config_test.dart
@@ -1,95 +1,66 @@
-// ignore_for_file: prefer_const_constructors
+// ignore: lines_longer_than_80_chars
+// ignore_for_file: prefer_const_constructors, prefer_const_declarations, use_named_constants, avoid_redundant_argument_values
+import 'package:checks/checks.dart';
 import 'package:kana_kit/kana_kit.dart';
 import 'package:test/test.dart';
 
-const passRomaji = false;
-const passKanji = true;
-const upcaseKatakana = false;
-const romanization = Romanization.hepburn;
-
 void main() {
   group('KanaKitConfig', () {
-    test('props are correct', () {
-      final actual = const KanaKitConfig(
+    KanaKitConfig buildSubject({
+      bool passRomaji = false,
+      bool passKanji = true,
+      bool upcaseKatakana = false,
+    }) {
+      return KanaKitConfig(
         passRomaji: passRomaji,
         passKanji: passKanji,
         upcaseKatakana: upcaseKatakana,
-      ).props;
+      );
+    }
 
-      final expected = [
-        passRomaji,
-        passKanji,
-        upcaseKatakana,
-        romanization,
-      ];
+    test('supports value equality', () {
+      check(buildSubject()).equals(buildSubject());
+    });
 
-      expect(actual, expected);
+    test('has correct hash code', () {
+      final subject = buildSubject();
+      check(subject).has((it) => it.hashCode, 'hashCode').equals(
+            subject.passRomaji.hashCode ^
+                subject.passKanji.hashCode ^
+                subject.upcaseKatakana.hashCode,
+          );
     });
-    group('constructor', () {});
+
     group('copyWith', () {
-      test(
-        'returns same object with updated passRomaji'
-        'when passRomaji is provided',
-        () {
-          const initial = false;
-          const changed = true;
+      test('returns same object when no arguments are provided', () {
+        check(buildSubject().copyWith()).equals(buildSubject());
+      });
 
-          expect(
-            KanaKitConfig(
-              passRomaji: initial,
-              passKanji: passKanji,
-              upcaseKatakana: upcaseKatakana,
-            ).copyWith(passRomaji: changed),
-            KanaKitConfig(
-              passRomaji: changed,
-              passKanji: passKanji,
-              upcaseKatakana: upcaseKatakana,
-            ),
-          );
-        },
-      );
-      test(
-        'returns same object with updated passKanji'
-        'when passKanji is provided',
-        () {
-          const initial = true;
-          const changed = false;
+      test('returns same object with updated passRomaji when provided', () {
+        const initial = true;
+        const changed = false;
 
-          expect(
-            KanaKitConfig(
-              passRomaji: passRomaji,
-              passKanji: initial,
-              upcaseKatakana: upcaseKatakana,
-            ).copyWith(passKanji: changed),
-            KanaKitConfig(
-              passRomaji: passRomaji,
-              passKanji: changed,
-              upcaseKatakana: upcaseKatakana,
-            ),
-          );
-        },
-      );
-      test(
-        'returns same object with updated upcaseKatakana'
-        'when upcaseKatakana is provided',
-        () {
-          const initial = false;
-          const changed = true;
+        check(buildSubject(passRomaji: initial).copyWith(passRomaji: changed))
+            .equals(buildSubject(passRomaji: changed));
+      });
 
-          expect(
-            KanaKitConfig(
-              passRomaji: passRomaji,
-              passKanji: passKanji,
-              upcaseKatakana: initial,
-            ).copyWith(upcaseKatakana: changed),
-            KanaKitConfig(
-              passRomaji: passRomaji,
-              passKanji: passKanji,
-              upcaseKatakana: changed,
-            ),
-          );
-        },
-      );
+      test('returns same object with updated passKanji when provided', () {
+        const initial = true;
+        const changed = false;
+
+        check(buildSubject(passKanji: initial).copyWith(passKanji: changed))
+            .equals(buildSubject(passKanji: changed));
+      });
+
+      test('returns same object with updated upcaseKatakana when provided', () {
+        const initial = true;
+        const changed = false;
+
+        check(
+          buildSubject(upcaseKatakana: initial)
+              .copyWith(upcaseKatakana: changed),
+        ).equals(buildSubject(upcaseKatakana: changed));
+      });
     });
   });
 }
diff --git a/test/models/romanization_test.dart b/test/models/romanization_test.dart
index a240106..f120b56 100644
--- a/test/models/romanization_test.dart
+++ b/test/models/romanization_test.dart
@@ -1,28 +1,15 @@
+import 'package:checks/checks.dart';
 import 'package:kana_kit/kana_kit.dart';
 import 'package:test/test.dart';
 
 void main() {
   group('Romanization', () {
-    test('props are correct', () {
-      final actual = Romanization.hepburn.props;
-
-      final expected = [
-        Romanization.hepburn.name,
-      ];
-
-      expect(actual, expected);
-    });
-    group('.is', () {
-      test('Hepburn is correct', () {
-        expect(Romanization.hepburn.isHepburn, isTrue);
-      });
+    test('supports value equality', () {
+      check(Romanization.hepburn).equals(Romanization.hepburn);
     });
 
     test('.toString is correct', () {
-      expect(
-        Romanization.hepburn.toString(),
-        'Romanization (Hepburn)',
-      );
+      check(Romanization.hepburn.toString()).equals('Romanization(Hepburn)');
     });
   });
 }
diff --git a/test/utils_test.dart b/test/utils_test.dart
index 55f704a..e6c4997 100644
--- a/test/utils_test.dart
+++ b/test/utils_test.dart
@@ -1,75 +1,63 @@
+import 'package:checks/checks.dart';
 import 'package:kana_kit/src/utils.dart';
 import 'package:test/test.dart';
 
 void main() {
-  group('Tuple', () {
-    const left = 20.7;
-    const right = 'Frederik';
-
-    test('props are correct', () {
-      // ignore: prefer_const_constructors
-      final actual = Tuple(left, right).props;
-      const expected = [left, right];
-
-      expect(actual, expected);
-    });
-    test('.toString is correct', () {
-      expect(
-        const Tuple(left, right).toString(),
-        'Tuple<double, String>(20.7, Frederik)',
-      );
-    });
-
-    test('left is correct', () {
-      expect(const Tuple(left, right).left, left);
-    });
-    test('right is correct', () {
-      expect(const Tuple(left, right).right, right);
-    });
-  });
-  group('Tuple Extensions', () {
+  group('TupleRecordIterableExtensions', () {
     const tuples = [
-      Tuple(1, 'a'),
-      Tuple(2, 'b'),
-      Tuple(3, 'c'),
+      (1, 'a'),
+      (2, 'b'),
+      (3, 'c'),
     ];
 
-    test('allLefts returns all left elements', () {
-      expect(tuples.allLefts, [1, 2, 3]);
+    test('allLefts returns first of every element', () {
+      check(tuples.allLefts).deepEquals([1, 2, 3]);
     });
-    test('allRights returns all right elements', () {
-      expect(tuples.allRights, ['a', 'b', 'c']);
+    test('allRights returns first of every element', () {
+      check(tuples.allRights).deepEquals(['a', 'b', 'c']);
     });
   });
+
   group('String Extensions', () {
     test('chars returns characters', () {
-      expect('abcdefg'.chars, ['a', 'b', 'c', 'd', 'e', 'f', 'g']);
+      check('abcdefg'.chars).deepEquals(['a', 'b', 'c', 'd', 'e', 'f', 'g']);
     });
+
     test('reversed returns reversed string', () {
-      expect('abcdefg'.reversed, 'gfedcba');
+      // cspell: disable
+      check('abcdefg'.reversed).equals('gfedcba');
+      // cspell: enable
     });
+
     test('code returns first code unit', () {
-      expect('abcdefg'.code, 'a'.codeUnitAt(0));
+      check('a'.code).equals('a'.codeUnitAt(0));
     });
+
     test('isUpperCase returns true if string is uppercase', () {
-      expect('abcdefg'.isUpperCase, isFalse);
-      expect('ABCDEFG'.isUpperCase, isTrue);
+      check('abcdefg'.isUpperCase).isFalse();
+      check('ABCDEFG'.isUpperCase).isTrue();
     });
+
     test('isLowerCase returns true if string is lowercase', () {
-      expect('abcdefg'.isLowerCase, isTrue);
-      expect('ABCDEFG'.isLowerCase, isFalse);
+      check('abcdefg'.isLowerCase).isTrue();
+      check('ABCDEFG'.isLowerCase).isFalse();
     });
+
     group('containsAny', () {
       test('return false if no candidates are provided', () {
-        expect('I love Tokyo'.containsAny([]), isFalse);
+        check('I love Tokyo'.containsAny([])).isFalse();
       });
+
       test('returns true if string contains any of the candidates', () {
-        expect('I love Tokyo'.containsAny(['Tokyo', 'Kyoto']), isTrue);
-      });
-      test('returns false if string does not contain any of the candidates',
-          () {
-        expect('I love Osaka'.containsAny(['Tokyo', 'Kyoto']), isFalse);
+        check('I love Tokyo'.containsAny(['Tokyo', 'Kyoto'])).isTrue();
       });
+
+      test(
+        'returns false if string does not contain any of the candidates',
+        () {
+          check('I love Osaka'.containsAny(['Tokyo', 'Kyoto'])).isFalse();
+        },
+      );
     });
   });
 }