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night-time going out; traveling at night (literary)
「夜行」 has another reading with different meanings.
五十音のや行にはや・ゆ・よがある。
The ya-row of the Japanese syllabary contains ya, yu, and yo.
五十音のヤ行の文字は三つしかない。
The ya-row of the syllabary has only three characters.
五十音図の也行には三つの仮名がある。
The ya-row of the syllabary chart has three kana.