Handakuten on ka, ki, ku, ke, ko (rendered as か゚, き゚, く゚, け゚, こ゚) represent the sound of ng in singing ([ŋ]), which is an allophone of /ɡ/ in many dialects of Japanese.
As /v/ does not exist in Japanese, this usage applies only to some modern loanwords and remains relatively uncommon, and e.g. Venus is typically transliterated as ビーナス (bīnasu) instead of ヴィーナス (vīnasu).
Precomposed characters exist for this method as well (/va/ ヷ /vi/ ヸ /vu/ ヴ /ve/ ヹ /vo/ ヺ), although most IMEs do not have a convenient way to enter them.
[citation needed] In Ainu texts, handakuten can be used with the katakana セ to make it a /t͡s/ sound, セ゚ ce [t͡se] (which is interchangeable with ツェ), and is used with small fu to represent a final p, ㇷ゚.
[citation needed] The dakuten can also be added to hiragana and katakana iteration marks, indicating that the previous kana is repeated with voicing: Both signs are relatively rare, but can occasionally be found in personal names such as Misuzu (みすゞ) or brand names such as Isuzu (いすゞ).
A longer, multi-character iteration mark called the kunojiten (〱), only used in vertical writing, may also have a dakuten added (〲).
Meiji-era descriptions of the Japanese "sound" system (either the actual phonology, or the orthography) in terms of "clear" and "muddy" always referenced the kana spelling and the two diacritics dakuten and handakuten.
One of such diacritics was a superscript version of the radical 氵 from the "muddy" character 濁, as in 婆氵 (ba rather than pa).
[11] The handakuten is an innovation by Portuguese Jesuits, who first used it in the Rakuyōshū, to accurately transcribe the consonant /p/ and its lenited form /f/, which had not been distinguished in domestic writing.