On August 17, 1180, the day of raising an army, Moritsuna's older brothers killed Nobuto TSUTSUMI who was considered to act as guardian of Kanetaka YAMAKI and a brave warrior, and then, Moritsuna went to Kanetaka's residence with Kagekado and cut off his head.
8月17日の挙兵の日、兄達が山木兼隆の後見で勇士とされた堤信遠を討った後、景廉と共に兼隆の邸宅へと赴きその首を獲った。