Hyakushuuta (The Set of One Hundred Poems, 百首歌) consists of one hundred poems as a unit, which are a type of waka composed with a predetermined number.
百首歌（ひゃくしゅうた）は、数を定めて詠う和歌（定数和歌）のひとつで、100首を単位として詠まれるもの。