After the fall of the Taira clan, he became a vassal of the Kamakura Shogunate, and 'Saburo TOKI,' who is recorded in the May 10 (in old calendar) article of "Azuma Kagami" to have accompanied MINAMOTO no Yoritomo in his summer hunting in the field at the foot of Mt. Fuji in 1193 is estimated to be Mitsuhira.
平家滅亡後は鎌倉幕府の御家人となり、建久4年(1193年)に源頼朝が富士裾野へ夏狩に出掛けた際、これに随行した「土岐三郎」は光衡であると推定されている(『吾妻鏡』同年5月10日(旧暦)条)。