Raiyu (1226 - February 7, 1304) was a Shingon Sect Buddhist monk who lived from the mid- to late-Kamakura period. He was born into the Dojogawa clan. His posthumous name was Shunon. His priest title was Shunonbo. He was born in Naga County, Kii Province.
Raiyu studied at Daidenpo-in Temple on Mt. Koya from where he went to learn Sanron Sect teachings, Kegon Sect teachings, yoga and the Yuishiki (consciousness-only) doctrine in Nara before studying the teachings of the Hirosawa School and the Hoonin School. He served both Daidenpo-in Temple and Daigo-ji Temple, and was appointed head priest of Chusho-in Temple on Mt. Koya in 1272. Raiyu was consecrated by Jissho and founded the Chushoin school in 1280 but friction arose with Kongobu-ji Temple, and in 1288 he relocated Daidenpo-in Temple and Mitsugo-in Temple to Negoro-ji Temple in Kii Province where he built the foundations of the Shingi Shingon Sect.