In 1179, Yoshitoki's sister Masako fell in love with the young Minamoto exile, Minamoto no Yoritomo, and they wed. The marriage was supported fully by the young heir, Yoshitoki. In 1180, Masako and Yoritomo had a daughter, Ō-Hime, who was very close with her maternal uncle, Yoshitoko. That same year, a disgruntled Prince Mochihito, a son of Go-Shirakawa, grew weary of the Taira leadership, believing he was denied the throne just so his young nephew, Emperor Antoku, who was half Taira, could be enthroned. He called the Minamoto leaders all over Japan to overthrow the Taira.