After MINAMOTO no Sanetomo, the third shogun was assassinated in 1219, the headship of OUCHI family seems to have been handed over to Korenobu from his father, Koreyoshi, and Korenobu succeeded to the Koreyoshi's position of Mino Province Shugo.
建保7年（1219年）に3代将軍源実朝が暗殺された後、父惟義から惟信へ家督が譲られたと見られ、惟義の美濃国の守護も引き継いだ。