The romanization of Japanese is the use of Latin script to write the Japanese language.^[1] This method of writing is sometimes referred to in Japanese as rōmaji (ローマ字, lit. 'Roman letters', [ɾoːma(d)ʑi] ^ⓘ or [ɾoːmaꜜ(d)ʑi]).

This article includes a list of general references, but it lacks sufficient corresponding inline citations. (February 2021)

Japanese is normally written in a combination of logographic characters borrowed from Chinese (kanji) and syllabic scripts (kana) that also ultimately derive from Chinese characters.

There are several different romanization systems. The three main ones are Hepburn romanization, Kunrei-shiki romanization (ISO 3602) and Nihon-shiki romanization (ISO 3602 Strict). Variants of the Hepburn system are the most widely used.

Romanized Japanese may be used in any context where Japanese text is targeted at non-Japanese speakers who cannot read kanji or kana, such as for names on street signs and passports and in dictionaries and textbooks for foreign learners of the language. It is also used to transliterate Japanese terms in text written in English (or other languages that use the Latin script) on topics related to Japan, such as linguistics, literature, history, and culture.

All Japanese who have attended elementary school since World War II have been taught to read and write romanized Japanese. Therefore, almost all Japanese can read and write Japanese by using rōmaji. However, it is extremely rare in Japan to use it to write Japanese (except as an input tool on a computer or for special purposes like in some logo design), and most Japanese are more comfortable in reading kanji and kana.

The earliest Japanese romanization system was based on Portuguese orthography. It was developed around 1548 by a Japanese Catholic named Anjirō.^{[2][citation needed]} Jesuit priests used the system in a series of printed Catholic books so that missionaries could preach and teach their converts without learning to read Japanese orthography. The most useful of these books for the study of early modern Japanese pronunciation and early attempts at romanization was the Nippo jisho, a Japanese–Portuguese dictionary written in 1603. In general, the early Portuguese system was similar to Nihon-shiki in its treatment of vowels. Some consonants were transliterated differently: for instance, the /k/ consonant was rendered, depending on context, as either c or q, and the /ɸ/ consonant (now pronounced /h/, except before u) as f; and so Nihon no kotoba ("The language of Japan") was spelled Nifon no cotoba. The Jesuits also printed some secular books in romanized Japanese, including the first printed edition of the Japanese classic The Tale of the Heike, romanized as Feiqe no monogatari, and a collection of Aesop's Fables (romanized as Esopo no fabulas). The latter continued to be printed and read after the suppression of Christianity in Japan (Chibbett, 1977).

From the mid-19th century onward, several systems were developed, culminating in the Hepburn system, named after James Curtis Hepburn who used it in the third edition of his Japanese–English dictionary, published in 1887. The Hepburn system included representation of some sounds that have since changed. For example, Lafcadio Hearn's book Kwaidan shows the older kw- pronunciation; in modern Hepburn romanization, this would be written Kaidan (lit. 'ghost tales').^{[citation needed]}

In addition to the standardized systems above, there are many variations in romanization, used either for simplification, in error or confusion between different systems, or for deliberate stylistic reasons.

Notably, the various mappings that Japanese input methods use to convert keystrokes on a Roman keyboard to kana often combine features of all of the systems; when used as plain text rather than being converted, these are usually known as wāpuro rōmaji. (Wāpuro is a blend of wādo purosessā word processor.) Unlike the standard systems, wāpuro rōmaji requires no characters from outside the ASCII character set.

While there may be arguments in favour of some of these variant romanizations in specific contexts, their use, especially if mixed, leads to confusion when romanized Japanese words are indexed. This confusion never occurs when inputting Japanese characters with a word processor, because input Latin letters are transliterated into Japanese kana as soon as the IME processes what character is input.

This chart shows in full the three main systems for the romanization of Japanese: Hepburn, Nihon-shiki and Kunrei-shiki:

This chart shows the significant differences among them. Despite the International Phonetic Alphabet, the /j/ sound in や, ゆ, and よ are never romanized with the letter J.

Japanese is written without spaces between words, and in some cases, such as compounds, it may not be completely clear where word boundaries should lie, resulting in varying romanization styles. For example, 結婚する, meaning "to marry", and composed of the noun 結婚 (kekkon, "marriage") combined with する (suru, "to do"), is romanized as one word kekkonsuru by some authors but two words kekkon suru by others.

There is no universally accepted style of romanization for the smaller versions of the vowels and y-row kana when used outside the normal combinations (きゃ, きょ, ファ etc.), nor for the sokuon or small tsu kana っ/ッ when it is not directly followed by a consonant. Although these are usually regarded as merely phonetic marks or diacritics, they do sometimes appear on their own, such as at the end of sentences, in exclamations, or in some names. The detached sokuon, representing a final glottal stop in exclamations, is sometimes represented as an apostrophe or as t; for example, あっ! might be written as a'! or at!.^{[citation needed]}

1603: Vocabvlario da Lingoa de Iapam (1603)

1604: Arte da Lingoa de Iapam (1604–1608)

1620: Arte Breve da Lingoa Iapoa (1620)

1848: Kaisei zoho Bango sen^[6] (1848)

The list below shows the Japanese readings of letters in Katakana, for spelling out words, or in acronyms. For example, NHK is read enu-eichi-kē (エヌ・エイチ・ケー). These are the standard names, based on the British English letter names (so Z is from zed, not zee), but in specialized circumstances, names from other languages may also be used. For example, musical keys are often referred to by the German names, so that B♭ is called bē (べー) from German B (German: [beː]).

Sources: Kōjien (7th edition), Daijisen (online version).

Note: Daijisen does not mention the name vī, while Kōjien does.

• Cyrillization of Japanese
• List of ISO romanizations
• Japanese writing system
• Transcription into Japanese