Shinkai 親快 (also read Chinkai; 1205–1271) was a Japanese Shingon master of the mid-Kamakura period, senior disciple of Kenjin 憲深 (1192–1263) in the Ninniku-yama 忍辱山 transmission line of the Ono-ryū. His principal scholarly contribution is the five-fascicle KR6t0204 Xìngxīn chāo (Kōshinshō), recorded from Kenjin’s oral teachings, the central document of the Ninniku-yama Ono-ryū. He rose to senior monastic office in the Ono-ryū hierarchy and was instrumental in the diffusion of the Ninniku-yama transmission into the Sanbō-in branch of mid-Kamakura Shingon.
Surviving work in the Kanripo corpus: KR6t0204 Kōshinshō (5 fasc., recorded from Kenjin).