Tachibana no Nagayasu (橘永愷; 988 – c. 1051), also known as Nōin (能因), was a Japanese poet and monk of the late Heian period.
Along with Izumi Shikibu, Nōin is one of "Thirty-six Medieval Poetry Immortals" of waka poetry selected by Fujiwara no Norikane (1107–1165).
Nōin is the author of Gengenshu and Nōin Utamakura.
Poetry
One of his poems is anthologized in the Ogura Hyakunin Isshu:
嵐吹く三室の山のもみぢ葉は 龍田の川の錦なりけり
arashi fuku Mimuro-no-yama no momijiba waTatsuta-no-kawa no nishiki narikeriBlown by storm winds, Mt. Mimuro's autumn leaves have become Tatsuta river's richly hued brocade!(Goshūi Wakashū 5:366)