Nōin

Tachibana no Nagayasu (橘永愷; 988 – c. 1051), also known was 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 authored of the Gengenshu and Nōin Utamakura.