In 900 when Emperor Daigo built Kaju-ji Temple as a religious service for the repose of the soul of his real mother, FUJIWARA no Inshi, Shoshun was invited to the service and became a kaisan (founder of a temple as the first chief priest).
900年（昌泰3年）醍醐天皇が生母である藤原胤子の追善のため勧修寺を建立した時、招かれてその開山となった。