Ryukan (1148 - January 21, 1228) was a Jodo sect priest from the late Heian period to the early Kamakura period. His father was FUJIWARA no Suketaka, Shonagon (Minor Counselor). His azana (popular names) were Kaiku Muga and Doku Muga. He was the founder of the Choraku-ji school of the Jodo sect.
In his childhood, Ryukan entered Enryaku-ji Temple on Mt. Hiei and learned Tendai doctrine under his uncle, Koen. There was an interchange between Ryukan and Jien, Tendai-zasu (head priest of the Tendai sect) through waka (a traditional Japanese poem of thirty-one syllables). After that, he became a pupil of Honen, the founder of Japan's Pure Land sect, and was given 'Senchaku Hongan Nenbutsu Shu' by Honen in March, 1204. Ryukan was regarded one of the major people who spread Senju Nenbutsu (the Single-Minded Recitation of the Nenbutsu) in the Karoku Persecution and was exiled to Mutsu Province. On the way, he edified Kanto warriors and passed away in Iiyama, Sagami Province (present day, Atsugi City, Kanagawa Prefecture).