Romaji

In Japanese, rōmaji (Japanese: ローマ字 "Roman characters") broadly refers to the Roman alphabet. rōmaji is sometimes referred to as rōmanji.

In English, the word is usually used to refer specifically to the writing of the Japanese language in Roman characters as opposed to the usual mix of kanji and kana.

Japanese may be written in rōmaji for many reasons: street signs for visiting foreigners; transcription of personal, company, or place names to be used in another language context; dictionaries and textbooks for learners of the language; or even simply for typographic emphasis.

There are a number of different romanization systems in use: the four main ones are Hepburn, Kunrei-shiki (Cabinet order or ISO 3602), Nihon-shiki (ISO 3602 Strict) and JSL. Simplified Hepburn (long-vowel omitted) is the most widely used outside Japan, and also on Japanese road signs and passports. The Japanese government, however, officially sanctions Kunrei for use in education.

See also: Cyrillization of Japanese Wikipedia:Manual of Style for Japan-related articles

Advantages of each romanization system

• Hepburn follows English phonology and so gives the best indication to English speakers of how a word is pronounced in Japanese. It was standardized as American National Standard System for the Romanization of Japanese (Modified Hepburn), but this status was abolished on October 6, 1994. Hepburn is used by Wikipedia and is the most common romanization system in use today, especially in the English-speaking world.
• Nihon-shiki follows Japanese kana spelling and so is easiest for Japanese speakers to compose and interpret. It has also been known as ISO 3602 Strict form.
• Kunrei-shiki is a modified Nihon-shiki with a touch of Hepburn; it is the official romanization system of the Japanese government (although many government agencies use Hepburn) and is taught in Japanese schools. It has been standardized as ISO 3602.
• JSL has a system of indicating pitch.

Non standard Romanization

In addition to the standardized systems above, one can see many other romanizations. These are used by many, either because they don't fully understand the system, or deliberately for stylistic reasons. Also, macrons and other diacritical symbols are often omitted or substituted for, both because of carelessness and difficulty in remembering or inputting them.

Romanizations that one is likely to come across "in the wild" include:

• oh for おお or おう (Hepburn ō).
• ou for おう (also Hepburn ō). This is known as wāpuro (word processor) spelling because it's the way you type おう into a computer with a Roman keyboard.
• ei for えい (Hepburn ē). Same as the use of ou. This usage is actually regular in JSL (and probably Nihon-shiki, possibly others) for loanwords written in katakana where エイ is pronounced differently from エー, for example スペイン is romanized as "supein."
• jya for じゃ (Hepburn ja) and so on. This seems to be the result of confusion between the Hepburn and the other romanization systems.
• dzu for づ (Hepburn zu). Another combination between multiple systems, in this case Hepburn and Nihon-shiki.
• la for ら (Hepburn ra) and so on. Since the Japanese consonant /r/ has a sound (IPA ɽ) that is somewhat between an English "r" and an "l" (and to some listeners sounds somewhat like a English "d"), this is unsurprising.
• a for ああ (Hepburn ā) and so on. In other words, merely failing to mark long vowels at all.
• na for んあ (Hepburn n'a) and so on.

While there may be arguments in favour of these romanizations, their use generally leads to even greater confusion, especially when Japanese words are romanized for indexing in a database.

Personal names can be subject to even more variation, with spellings depending on the individual's preference. For example, the manga artist Yasuhiro Nightow's family name would be more conventionally written in Hepburn as Naitō.

Example words written in each romanization system

(TODO: The JSL column needs pitch indicators.)

Differences between romanization systems