There is some discussion over the reason for his entering the priesthood; however, it is difficult to say which one is correct but one of the theories in which Saigyo was in love with FUJIWARA no Shoshi who was a mistress of Emperor Shirakawa and Chugu (the term for a woman at the highest position as a mistress of an emperor) of Tobain (the Retired Emperor Toba).
その動機には諸説あっていずれとも定めがたいが、一説に白河天皇の愛妾にして鳥羽院の中宮であった藤原璋子への恋着のゆえであったとも言われる。