Mansai served as the twenty-fifth monzeki (head priest of the temple, formerly led by the sect founder) of the Sanboin Temple, and also held the post of seventy-fourth zasu (temple head priest) of Daigo-ji Temple from 1395 to 1434, creating a precedent for the monzeki of Sanboin Temple concurrently holding the post of zasu of Daigo-ji Temple.
三宝院25世門跡となり、応永2年（1395年）から永享6年（1434年）の間醍醐寺第74代座主を務め、以後、三宝院門跡が醍醐寺座主を兼ねる例となった。