According to "Koyo Gunka," one reason that Shingen became a priest was that he intended to acquire the position of daisojo (a Buddhist priest of the highest order) after entering priesthood.
『甲陽軍鑑』の中で信玄出家の理由の一つに、出家することで大僧正の地位を手に入れるといった目的もあったとの記述も見られる。