In Japanese, rōmaji (ローマ字 "Roman characters") broadly refers to the Roman alphabet.
In English, the word refers specifically to the writing of the Japanese language in Roman characters as opposed to the usual mix of kanji and kana.
Rōmaji is sometimes mispelled as Rōmanji, and although seen with some frequency, this spelling does not represent any Japanese spelling or pronunciation of the word.
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 three main ones are Hepburn, Kunrei-shiki (Cabinet order or ISO 3602), and Nihon-shiki (ISO 3602 Strict). Hepburn (long-vowel omitted) is the most widely used. Modified Hepburn, which uses a macron to indicate some long vowels and an apostrophe to note the separation of easily confused syllables (for example, the name じゅんいちろう is written with the syllables jun-ichi-ro and u, and is romanized as Jun'ichirō in Modified Hepburn) is widely used in Eastern Japan and among foreign students and academics.
In addition to the standardized systems above, one can see many other romanizations. These are used by many people, either because they do not fully understand the particular system they are attempting to use, or for deliberate stylistic reasons. Macrons and other diacritical symbols are often omitted or substituted for, because of carelessness, difficulty in remembering or inputting them, or simply unavailability in one's character set (although this last reason is becoming less frequent with the widespread introduction of Unicode).
Also commonly seen are wāpuro rōmaji, referring to the various methods that IMEs use for converting keystrokes on a roman keyboard to kana. (Wāpuro derives from wādo purosessā [word processor].) Unlike the standard systems, wāpuro rōmaji requires no characters from outside the ASCII character set.
Romanizations that one is likely to come across "in the wild" include:
While there may be arguments in favour of these romanizations in specific contexts, their use (especially if mixed) 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.
In addition, words and names that have established English spellings, such as Tokyo, Kyoto, and Kanto, are sometimes written as they are in English, without regard for the rules of romanization.
| English | Japanese | Kana spelling | Romanization | ||
|---|---|---|---|---|---|
| Modified Hepburn | Kunrei-shiki | Nihon-shiki | |||
| Roman characters | ローマ字 | ローマじ | rōmaji | rômazi | rōmazi |
| Mount Fuji | 富士山 | ふじさん | Fujisan | Huzisan | Huzisan |
| tea | お茶 | おちゃ | ocha | otya | otya |
| governor | 知事 | ちじ | chiji | tizi | tizi |
| shrink | 縮む | ちぢむ | chijimu | tizimu | tidimu |
| Kana | Modified Hepburn | Kunrei-shiki | Nihon-shiki |
|---|---|---|---|
| うう | ū | û | ū |
| おう, おお | ō | ô | ō |
| し | shi | si | si |
| しゃ | sha | sya | sya |
| しゅ | shu | syu | syu |
| しょ | sho | syo | syo |
| じ | ji | zi | zi |
| じゃ | ja | zya | zya |
| じゅ | ju | zyu | zyu |
| じょ | jo | zyo | zyo |
| ち | chi | ti | ti |
| つ | tsu | tu | tu |
| ちゃ | cha | tya | tya |
| ちゅ | chu | tyu | tyu |
| ちょ | cho | tyo | tyo |
| ぢ | ji | zi | di |
| づ | zu | zu | du |
| ぢゃ | ja | zya | dya |
| ぢゅ | ju | zyu | dyu |
| ぢょ | jo | zyo | dyo |
| ふ | fu | hu | hu |