平治の乱
During the Heiji Rebellion in 1159, the Taira clan under Taira no Kiyomori, defeated the Minamoto clan with the support of Cloistered Emperor Go-Shirakawa. Minamoto no Yoshitomo, leader of the Minamoto clan, was executed while his sons and daughters were either executed or sent to nunneries. Of his surviving sons, Minamoto no Yoshitsune and Minamoto no Noriyori were forced into priesthood, while Minamoto no Yoritomo, at the age of thirteen, was exiled to Izu in the domain of Hōjō Tokimasa. While this was happening, Masako was barely an infant. The Taira under Kiyomori now were in successful control of Japan.