He was originally a government official from lower-ranking nobles that served the Imperial Court, went down to Kamakura to be an official as a close adviser for MINAMOTO no Yoritomo, and contributed to the establishment of the Kamakura bakufu.
最初は朝廷に仕える下級貴族のいわゆる官人であったが、鎌倉に下って源頼朝の側近官僚となり、鎌倉幕府の創設に貢献した。