His mother was a daughter of MINAMOTO no Yoshinari (the earliest ancestor of the Satake clan), the leader of Hitachi-Genji (Minamoto clan) who had strong power in the northern part of Hitachi Province.
母は、常陸国の北部に強い勢力を誇った常陸源氏の棟梁源義業（佐竹氏の祖）の娘。