At first a plain Prince rather than an Imperial Prince, after becoming Seii taishogun he was made a commoner and received the surname, MINAMOTO, and used the name MINAMOTO no Koreyasu (a member of the Gosaga-Genji).
初めは親王宣下がなされず「惟康王」と呼ばれ、征夷大将軍に就任すると臣籍降下し源姓を賜与され、「源惟康」と名乗る（後嵯峨源氏）。