Chōonpu

	kana gojūon
	n	wa	ra	ya	ma	ha	na	ta	sa	ka	a
sokuon		wi	ri		mi	hi	ni	chi	shi	ki	i
dakuten			ru	yu	mu	fu	nu	tsu	su	ku	u
chōonpu		we	re		me	he	ne	te	se	ke	e
		wo	ro	yo	mo	ho	no	to	so	ko	o

The chōonpu (長音符^?), also known as onbiki (音引き^?), bōbiki (棒引き^?), or Katakana-Hiragana Prolonged Sound Mark by the Unicode Consortium, is a Japanese symbol which indicates a chōon, or a long vowel of two morae in length. Its form is a horizontal or vertical line in the center of the text with the width of one kanji or kana character. It is written horizontally (ー) in horizontal text and vertically in vertical text. The chōonpu is usually used to indicate a long vowel sound in katakana writing, rarely in hiragana writing, and never in romanized Japanese. The chōonpu is a distinct mark from the dash, and in most Japanese typefaces it can easily be distinguished.

The symbol is sometimes used with hiragana, for example in the signs of ramen restaurants, which are sometimes written らーめん in hiragana. However, usually, hiragana does not use the chōonpu but another vowel kana to express this sound. The following table shows the usual hiragana equivalents used to form a long vowel, using the ha-gyō as an example.

Romaji	Hiragana	Katakana
hā	はあ	ハー
hī	ひい	ヒー
fū / hū	ふう	フー
hē (hei)	へい	ヘー
hē (hee)	へえ
hō (hou)	ほう	ホー
hō (hoo)	ほお

In addition to Japanese, chōonpu are also used in katakana Okinawan writing systems to indicate two morae. The Sakhalin dialect of Ainu also uses chōonpu in its katakana writing for long vowels.

In Unicode, the fullwidth form has the value U+30FC (ー), while the halfwidth form has the value U+FF70 (ｰ), both for horizontal writing.