warrior whose service to the powerful Fujiwara Family, which dominated Japan between 857 and 1160, helped raise the Seiwa branch of the Minamoto clan (also known as the Seiwa Genji) to a position of preeminence.

In 1028 the Fujiwaras, no longer willing to fight their own battles, hired Yorinobu to quell a rebellion that had broken out in eastern Japan. His success in crushing the rebellion three years later established his clan's influence in the east and strengthened his own position at court. Thereafter the Minamotos were known as the “claws and teeth” of the Fujiwaras, and their influence grew until, by the 12th century, they dominated all Japan.