In 1981, his father, Kosho, who was the Hoshi (successor to an abbacy) to the Otani school, Shinshu sect and the chief priest of Tokyo Branch Temple, Tokyo Hongan-ji Temple, was forced to separate his temple from the Otani school Shinshu sect because of a conflict with the Naikyoku (intra-ministerial bureau), and was removed from the priesthood; thereby, Koken succeeded as hoshi (successor of principle).
1981年（昭和56年）、真宗大谷派の法嗣（新門＝法主後継者）であった父・光紹が、真宗大谷派内局（当局）との確執（「お東騒動」）により、自身が住職であった真宗大谷派東京別院東京本願寺を宗派から独立させ、真宗大谷派の僧籍から離れたことから、父に代って法嗣となった。