According to "the Azuma Kagami" (the Mirror of the East), Kagemitsu started to Kamakura on June 21, 1185 as an envoy of Yoshitsune and sent the following message to Yoritomo, the elder brother of Yoshitsune: 'on the 21st we will arrivie at Sako Station with the father and son of TAIRA no Munemori and TAIRA no Kiyomori who are captives of the Battle of Dan no Ura and we will arrive at Kamakura tomorrow.'
『吾妻鏡』によると、元暦2年（1185年）5月15日義経の使者として鎌倉へ向かい「壇ノ浦の合戦の捕虜である平宗盛・平清宗親子を連れ15日に酒匂駅に着くので、明日鎌倉へ入りする。」と伝える。