During the Insei period, the three Retired Emperors; Emperor Shirakawa, Emperor Toba, and Emperor Goshirakawa entered into priesthood by their own will to become a priest, and intensified one's authority through Buddhism.
院政期には白河天皇、鳥羽天皇、後白河天皇の3上皇がみずから出家して法皇となり、仏教によって権威を高めた。