He was born eldest son of MINAMOTO no Chikasue, Kaga no Gon no kami (Provisional Governor of Kaga Province), and adopted by Michichika KOGA of naidaijin (Minister of the Interior), who belonged to the Murakami-Genji (Minamoto clan), when he was nine years old.
加賀権守源親季の長男として生まれ、9歳の春、村上源氏の内大臣久我通親の養子となる。