Ikko Shunsho, a descendant of the Kusano clan in Chikugo Province, was originally a monk of the Chinzei school of the Jodoshu sect; according to another opinion, he was a monk of the Nishiyama Jodoshu sect.
一向は筑後国草野氏の出身で初めは浄土宗鎮西派（西山派という異説もある）の僧侶であった。