When MINAMOTO no Yoritomo, of the Kawachi-Genji clan, was expatriated to Izu--a province held in the fiefdom of MINAMOTO no Yorimasa, of the Settsu-Genji clan--Tokimasa was ordered to keep an eye on Yoritomo.
河内源氏の源頼朝が、摂津源氏の源頼政の知行国である伊豆に流された時、頼朝の監視役となる。