According to "Heike Monogatari" (The tale of the Taira clan), Yoshimori said 'Even if my father dies and my descendants die, nothing makes me happier than seeing Lord Yoritomo. Please pursue your original dream and take the country. When it happens, please appoint me as the Samurai-dokoro betto. After FUJIWARA no Tadakiyo who used to be the Kazusa no suke (Assistant Governor of Kazusa Province) was appointed to the Samurai-dokoro betto for eight provinces by the Taira family, I envied his power and I have always prayed to the Hachiman Daibosatsu (Great Bodhisattava Hachiman) that one day I would like to become one'.
『平家物語』によれば、この時、義盛は「父が死に、子孫が死んでも、頼朝公のお姿を見ればこれに過ぎる悦びはない。どうか本懐を遂げて天下をお取りください。その暁には私を侍所の別当に任じてください。上総国だった藤原忠清が平家から八カ国の侍所別当に任じられ、その威勢をうらやましく思い、いつか自分もと八幡大菩薩に祈願いたしたのです」と願ったという。