According to "Eiga Monogatari (A Tale of Flowering Fortunes)" and "Okagami (The Great Mirror)," the reason the Emperor became a priest was that his favorite high-ranking lady in the court (a wife of an Emperor), FUJIWARA no Shishi had died while pregnant, and there is a further record in "Okagami (The Great Mirror)" that FUJIWARA no Kaneie plotted to let his daughter's grandchild, Prince Yasuhito (Emperor Ichijo), succeed the throne.
突然の出家について、『栄花物語』『大鏡』などは寵愛した女御藤原忯子が妊娠中に死亡したことを素因とするが、『大鏡』では更に、藤原兼家が、外孫の懐仁（やすひと）親王（一条天皇）を即位させる為に陰謀を巡らした事を伝えている。