According to legend, ghosts would appear at Zenrin-ji-dono night after night and trouble the Cloistered Emperor Kameyama and his staff, but Mukan Fumon brought his disciples and simply sat and meditated (zazen) until the ghosts left, which so impressed the Cloistered Emperor that he invited Mukan to serve as chief priest.
伝承によれば、この頃禅林寺殿に夜な夜な妖怪変化が出没して亀山法皇やお付きの官人たちを悩ませたが、無関普門が弟子を引き連れて禅林寺殿に入り、静かに座禅をしただけで妖怪変化は退散したので、亀山法皇は無関を開山に請じたという。