It is said that Shinbutsu studied under Shinran at Inada Soan (now Sainen-ji Temple in Inada, Kasama City, Ibaraki Prefecture) around 1224 and he had Shinran shave his head to become a priest in 1225.
1224年（元仁元年）ごろ稲田草庵（現在茨城県笠間市稲田にある西念寺）で親鸞に師事してその教を受け、翌1225年（嘉禄元年）に親鸞より剃髪を受けたという。