The yōon(Japanese: 拗音 (ようおん)) is a feature of the Japanese language in which a mora is formed with an added [j] sound, i.e., palatalized, or (more rarely in the modern language) with an added [w] sound, i.e. labialized.

Yōon are represented in hiragana using a kana ending in i, such as き (ki) or に (ni), plus a smaller version of one of the three y kana, (ya), (yu) or (yo). For example, 今日 (kyō, 'today') is written きょう [kʲoː], using a small version of the kana. Contrast this with 器用 (kiyō, 'skillful'), which is written きよう [kijoː], with a full-sized よ kana. In historical kana orthography, yōon were not distinguished with the smaller kana, and had to be determined by context.

In earlier stages of Japanese, and in certain dialects, yōon can also be formed with the kana wa, wi, we, and wo; for example, くゎ/クヮ (kwa), くゐ/クヰ (kwi), くゑ/クヱ (kwe), くを/クヲ (kwo).[citation needed] Although obsolete in modern Japanese, kwa and kwi can still be found in several of the Ryukyuan languages today (e.g. Okinawan), while kwe is formed with the digraph くぇ. Kwa also appears in the Kagoshima dialect. Instead of the kana き, these are formed with the kana for ku, く/ク. Some older transliterations in English follow the earlier pronunciation, e.g. Kwaidan, Kwannon, and such yōon may appear in loanwords e.g. ムジカ・アンティクヮ・ケルン "Musica Antiqua Köln". They were also used to write Hakka in Taiwan under Japanese rule (called Cantonese kana[ja]).

Table

Yōon 拗音
Katakana ya yu yo ki キャ kya キュ kyu キョ kyo shi シャ sha シュ shu ショ sho chi チャ cha チュ chu チョ cho ni ニャ nya ニュ nyu ニョ nyo hi ヒャ hya ヒュ hyu ヒョ hyo mi ミャ mya ミュ myu ミョ myo ri リャ rya リュ ryu リョ ryo Dakuten gi ギャ gya ギュ gyu ギョ gyo ji ジャ ja ジュ ju ジョ jo ji ヂャ ja ヂュ ju ヂョ jo bi ビャ bya ビュ byu ビョ byo Handakuten pi ピャ pya ピュ pyu ピョ pyoHiragana ya yu yo ki きゃ kya きゅ kyu きょ kyo shi しゃ sha しゅ shu しょ sho chi ちゃ cha ちゅ chu ちょ cho ni にゃ nya にゅ nyu にょ nyo hi ひゃ hya ひゅ hyu ひょ hyo mi みゃ mya みゅ myu みょ myo ri りゃ rya りゅ ryu りょ ryo Dakuten gi ぎゃ gya ぎゅ gyu ぎょ gyo ji じゃ ja じゅ ju じょ jo ji ぢゃ ja ぢゅ ju ぢょ jo bi びゃ bya びゅ byu びょ byo Handakuten pi ぴゃ pya ぴゅ pyu ぴょ pyo
Katakana
ya yu yo
kiキャ kyaキュ kyuキョ kyo
shiシャ shaシュ shuショ sho
chiチャ chaチュ chuチョ cho
niニャ nyaニュ nyuニョ nyo
hiヒャ hyaヒュ hyuヒョ hyo
miミャ myaミュ myuミョ myo
riリャ ryaリュ ryuリョ ryo
Dakuten
giギャ gyaギュ gyuギョ gyo
jiジャ jaジュ juジョ jo
jiヂャ jaヂュ juヂョ jo
biビャ byaビュ byuビョ byo
Handakuten
piピャ pyaピュ pyuピョ pyo
Hiragana
ya yu yo
kiきゃ kyaきゅ kyuきょ kyo
shiしゃ shaしゅ shuしょ sho
chiちゃ chaちゅ chuちょ cho
niにゃ nyaにゅ nyuにょ nyo
hiひゃ hyaひゅ hyuひょ hyo
miみゃ myaみゅ myuみょ myo
riりゃ ryaりゅ ryuりょ ryo
Dakuten
giぎゃ gyaぎゅ gyuぎょ gyo
jiじゃ jaじゅ juじょ jo
jiぢゃ jaぢゅ juぢょ jo
biびゃ byaびゅ byuびょ byo
Handakuten
piぴゃ pyaぴゅ pyuぴょ pyo
Gō Yōon (合拗音; Closed Yōon) – Obsolete
wa wi we
kuくゎ kwa(くゐ) kwi(くゑ) kwe
guぐゎ gwa(ぐゐ) gwi(ぐゑ) gwe

Other representations

Braille
YōonYōon + DakutenYōon + Handakuten-w-

In Japanese Braille, Yōon is indicated with one of the yōon, yōon+dakuten, or yōon+handakuten prefixes.

Unlike in kana, Braille yōon is prefixed to the -a/-u/-o morae, rather than appending ya, yu or yo to an -i kana, e.g. kyu: きゅ - ki + yu ⠈⠩ - yōon + ku. Likewise, the -w- morae are indicated by a prefix of the -a/-i/-e/-o morae, rather than an -u mora, e.g. くぁ / くゎ (kwa) = -w- + ka: ⠢⠡.