Hisanao was a grandson (or a son) of MINAMOTO no Mitsusue of Saga Genji who was transferred to Hizen Province as a shokan (officer entrusted with local management by the lord of the private estate) of the Kanzaki Manor of Tobain-ryo Estates (Hizen Province), a private estate of the Imperial Family.
肥前国の天皇家直轄荘園の神埼荘(鳥羽院領神埼荘)に荘官として下向した嵯峨源氏の源満末の孫（あるいは子）。