Romanization Systems

There have been several systems used to transliterate Japanese with Latin characters.

The Kunrei-skiki Method

The Kunrei-shiki 訓令式 was promulgated by the Ministry of Education and remains the means of Japanese romanization taught in schools and used in official documents¹. New かな extensions are hard to apply with this system, resulting in unintended ambiguity. For example, ティ and チ are both rendered as [ti].

	ア/あ A	イ/い I	ウ/う U	エ/え E	オ/お O	ャ/ゃ [C]+ya	ュ/ょ [C]+yu	ョ/ょ [C]+yo
K	カ/か KA	キ/き KI	ク/く KU	ケ/け KE	コ/こ KO	キャ きゃ KYA	キュ きゅ KYU	キョ きょ KYO
S	サ/さ SA	シ/し SI	ス/す SU	セ/せ SE	ソ/そ SO	シャ しゃ SYA	シュ しゅ SYU	ショ しょ SYO
T	タ/た TA	チ/ち TI	ツ/つ TU	テ/て TE	ト/と TO	チャ ちゃ TYA	チュ ちゅ TYU	チョ ちょ TYO
N	ナ/な NA	ニ/に NI	ヌ/ぬ NU	ネ/ね NE	ノ/の NO	ニャ にゃ NYA	ニュ にゅ NYU	ニョ にょ NYO
H	ハ/は HA	ヒ/ひ HI	フ/ふ HU	ヘ/へ HE	ホ/ほ HO	ヒャ ひゃ HYA	ヒュ ひゅ HYU	ヒョ ひょ HYO
M	マ/ま MA	ミ/み MI	ム/む MU	メ/め ME	モ/も MO	ミャ みゃ MYA	ミュ みゅ MYU	ミョ みょ MYO
Y	ヤ/や YA		ユ/ゆ YU		ヨ/よ YO
R	ラ/ら RA	リ/り RI	ル/る RU	レ/れ RE	ロ/ろ RO	リャ りゃ RYA	リュ りゅ RYU	リョ りょ RYO
W	ワ/わ WA	ヰ/ゐ I		ヱ/ゑ E	ヲ/を O
					ン/ん N(‘)
G	ガ/が GA	ギ/ぎ GI	グ/ぐ GU	ゲ/げ GE	ゴ/ご GO	ギャ ぎゃ GYA	ギュ ぎゅ GYU	ギョ ぎょ GYO
Z	ザ/ざ ZA	ジ/じ ZI	ズ/ず ZU	ゼ/ぜ ZE	ゾ/ぞ ZO	ジャ じゃ ZYA	ジュ じゅ ZYU	ジュ じょ ZYO
D	ダ/だ DA	ヂ/ぢ ZI	ヅ/づ ZU	デ/で DE	ド/ど DO	ヂャ ぢゃ ZYA	ヂュ ぢゅ ZYU	ヂョ ぢょ ZYO
B	バ/ば BA	ビ /び BI	ブ/ぶ BU	ベ/べ BE	ボ/ぼ BO	ビャ びゃ BYA	ビュ びゅ BYU	ビョ びょ BYO
P	パ/ぱ PA	ピ/ぴ PI	プ/ぷ PU	ペ/ぺ PE	ポ/ぽ PO	ピャ ぴゃ PYA	ピュ ぴゅ PYU	ピョ ぴょ PYO

Orthographic Rules

1. The particles ヘ, ハ・は, and ヲ・を are rendered as “e”, “wa”, and “o” respectively. 
2. Long vowels are represented with a circumflex mark (ˆ).
3. ン・ん is written as “n'” with an apostrophe before “y.”
4. Double consonants are written by doubling the first letter of the corresponding romanization for said character – ex. [ッチャ = TTYA].

The Nihon-shiki Method

The Nihon-shiki 日本式 method or romanization was created by Aikitsu Tanakadate 田中館愛橘, and it is the basis for the Kunrei-shiki 訓令式 method, with the only differences being as follows:

•  Yotsugana differences are maintained – ex. [じゅ = ZYU, [ぢゅ = DYU], [ず = ZU], [づ = DU]
•  All ワ行 sounds retain [w] – ex. [ヰ・ゐ = WI].
•  [kw] and [gw] are retained – ex. [関西（くわんさい）= KWANSAI].

	ア/あ A	イ/い I	ウ/う U	エ/え E	オ/お O	ャ/ゃ [C]+ya	ュ/ゅ [C]+yu	ョ/ょ [C]+yo
K	カ/か KA	キ/き KI	ク/く KU	ケ/け KE	コ/こ KO	キャ きゃ KYA	キュ きゅ KYU	キョ きょ KYO
S	サ/さ SA	シ/し SI	ス/す SU	セ/せ SE	ソ/そ SO	シャ しゃ SYA	シュ しゅ SYU	ショ しょ SYO
T	タ/た TA	チ/ち TI	ツ/つ TU	テ/て TE	ト/と TO	チャ ちゃ TYA	チュ ちゅ TYU	チョ ちょ TYO
N	ナ/な NA	ニ/に NI	ヌ/ぬ NU	ネ/ね NE	ノ/の NO	ニャ にゃ NYA	ニュ にゅ NYU	ニョ にょ NYO
H	ハ/は HA	ヒ/ひ HI	フ/ふ HU	ヘ/へ HE	ホ/ほ HO	ヒャ ひゃ HYA	ヒュ ひゅ HYU	ヒョ ひょ HYO
M	マ/ま MA	ミ/み MI	ム/む MU	メ/め ME	モ/も MO	ミャ みゃ MYA	ミュ みゅ MYU	ミョ みょ MYO
Y	ヤ/や YA		ユ/ゆ YU		ヨ/よ YO
R	ラ/ら RA	リ/り RI	ル/る RU	レ/れ RE	ロ/ろ RO	リャ りゃ RYA	リュ りゅ RYU	リョ りょ RYO
W	ワ/わ WA	ヰ/ゐ WI		ヱ/ゑ WE	ヲ/を WO
					ン/ん N(‘)
G	ガ/が GA	ギ/ぎ GI	グ/ぐ GU	ゲ/げ GE	ゴ/ご GO	ギャ ぎゃ GYA	ギュ ぎゅ GYU	ギョ ぎょ GYO
Z	ザ/ざ ZA	ジ/じ ZI	ズ/ず ZU	ゼ/ぜ ZE	ゾ/ぞ ZO	ジャ じゃ ZYA	ジュ じゅ ZYU	ジュ じょ ZYO
D	ダ/だ DA	ヂ/ぢ DI	ヅ/づ DU	デ/で DE	ド/ど DO	ヂャ ぢゃ DYA	ヂュ ぢゅ DYU	ヂョ ぢょ DYO
B	バ/ば BA	ビ /び BI	ブ/ぶ BU	ベ/べ BE	ボ/ぼ BO	ビャ びゃ BYA	ビュ びゅ BYU	ビョ びょ BYO
P	パ/ぱ PA	ピ/ぴ PI	プ/ぷ PU	ペ/ぺ PE	ポ/ぽ PO	ピャ ぴゃ PYA	ピュ ぴゅ PYU	ピョ ぴょ PYO
KW	クヮ くゎ KWA
GW	グヮ グヮ GWA

The Hepburn Method

The Hepburn Romanization system, ヘボン式ローマ字, is credited to James Curtis Hepburn who transcribed the Japanese language into English letters. While the Kunrei-shiki 訓令式 method transcribes Japanese morae phonologically rather than phonemically, it has had no need of being updated over time, whereas the Hepburn system has been updated over time to reflect changes in Japanese pronunciation. For the purpose of studying Japanese, however, only the modern iteration of the Hepburn system is needed.

	ア/あ A	イ/い I	ウ/う U	エ/え E	オ/お O	ャ/ゃ [C]+ya	ュ/ょ [C]+yu	ョ/ょ [C]+yo
K	カ/か KA	キ/き KI	ク/く KU	ケ/け KE	コ/こ KO	キャ きゃ KYA	キュ きゅ KYU	キョ きょ KYO
S	サ/さ SA	シ/し SHI	ス/す SU	セ/せ SE	ソ/そ SO	シャ しゃ SHA	シュ しゅ SHU	ショ しょ SHO
T	タ/た TA	チ/ち CHI	ツ/つ TSU	テ/て TE	ト/と TO	チャ ちゃ CHA	チュ ちゅ CHU	チョ ちょ CHO
N	ナ/な NA	ニ/に NI	ヌ/ぬ NU	ネ/ね NE	ノ/の NO	ニャ にゃ NYA	ニュ にゅ NYU	ニョ にょ NYO
H	ハ/は HA	ヒ/ひ HI	フ/ふ FU	ヘ/へ HE	ホ/ほ HO	ヒャ ひゃ HYA	ヒュ ひゅ HYU	ヒョ ひょ HYO
M	マ/ま MA	ミ/み MI	ム/む MU	メ/め ME	モ/も MO	ミャ みゃ MYA	ミュ みゅ MYU	ミョ みょ MYO
Y	ヤ/や YA		ユ/ゆ YU		ヨ/よ YO
R	ラ/ら RA	リ/り RI	ル/る RU	レ/れ RE	ロ/ろ RO	リャ りゃ RYA	リュ りゅ RYU	リョ りょ RYO
W	ワ/わ WA	ヰ/ゐ (W)I		ヱ/ゑ (W)E	ヲ/を (W)O
					ン/ん N(‘)
G	ガ/が GA	ギ/ぎ GI	グ/ぐ GU	ゲ/げ GE	ゴ/ご GO	ギャ ぎゃ GYA	ギュ ぎゅ GYU	ギョ ぎょ GYO
Z	ザ/ざ ZA	ジ/じ JI	ズ/ず ZU	ゼ/ぜ ZE	ゾ/ぞ ZO	ジャ じゃ JA	ジュ じゅ JU	ジュ じょ JO
D	ダ/だ DA	ヂ/ぢ (D)JI	ヅ/づ (D)ZU	デ/で DE	ド/ど DO	ヂャ/ぢゃ (D)JA	ヂュ ぢゅ (D)JU	ヂョ ぢょ (D)JO
B	バ/ば BA	ビ /び BI	ブ/ぶ BU	ベ/べ BE	ボ/ぼ BO	ビャ びゃ BYA	ビュ びゅ BYU	ビョ びょ BYO
P	パ/ぱ PA	ピ/ぴ PI	プ/ぷ PU	ペ/ぺ PE	ポ/ぽ PO	ピャ/ぴゃ PYA	ピュ ぴゅ PYU	ピョ ぴょ PYO

Orthographic Rules

1.  ヰ・ゐ and ヱ・ゑ, although obsolete are generally rendered as [i] and [e] respectively, but writers may chose to reinsert [w] to reflect older pronunciation.
2.  The particles ヘ, ハ・は, and ヲ・を are rendered as “e”, “wa”, and “(w)o” respectively. (W)o is left to personal preference with many resources sticking to [wo] to differentiate ヲ・を from オ・お.
3.  ン・ん is usually spelled as [n], with [n’] used when it is before a vowel. In recent years, [m] is the preferred spelling when ン・ん comes before the labial consonants [m], [b], and [p].
4. All long vowels except long /i/ are written with macrons. For loanwords, however, a macron may be used even with /i/.
5. Geminate consonants are typically written by doubling the first letter, but for geminate [ch], ッチャ・っちゃ, it is rendered as [tch].

JSL Romanization

The JSL Romanization created by Eleanor Jorden and introduced in her work Japanese: The Spoken Language is heavily based off the 訓令式 Romanization System but with some important differences. 

1. All long vowels are written by doubling the vowel letter. [Ou] is only seen when they are rendered as separate sounds rather than as a long /o/.
2. [ŋ] is distinguished as ḡ.
3. [N’] is written as n̄.
4. An acute accent is used to denote the first high-pitch mora in a word.
5. A grave accent shows the last high-pitch mora in a word.
6. A circumflex shows the only high-pitch mora in a word.

1. Despite its official status, the 訓令式 method of romanization has never been nearly as widespread in society as the Hepburn system. This is so much so that the Hepburn system has already been used in official circumstances such as passports and road signs for decades despite Cabinet decrees incentivizing otherwise. As of 2024, the Japanese government has announced that it will, in fact, abandon the 訓令式 method in favor of the Hepburn system. When this change will take place and to what extent revisions to the Hepburn system will be implemented have yet to be announced. ↩︎