Motomichi's family background are still entirely unknown, but it has been thought that he was a local government officer because he had access to the Governor's seal and the key of the provincial shoso, and some historical materials say he was a sani.
基通の出自、系譜については全く不明であるが、国司の印や国の正倉の鍵に近づけ、史料に散位と記載されていることから、在庁官人であると見られている。