白河天皇
In 1086, Emperor Shirakawa in his turn abdicated in favor of his son, Emperor Horikawa, who was four years old at the time. Shirakawa's objective appeared to be the protection of his son from his younger brother (Horikawa's uncle), who presented a serious threat of becoming a pretender to the throne, but after his retirement Shirakawa exerted his personal power to set the cloistered rule system in motion.