The castle lords had great authority and shared a part of the power of kokushi (provincial governor), as they ruled gunji (local magistrates) appointed to the gun (province) and barbarians residing within, and had a command of an army of soldiers and barbarians.
城司の権限は大きく、国司の権限を分掌し、設置された辺郡の郡司や辺郡内に居住する俘囚を支配し、鎮兵や俘囚により編成された俘軍の指揮権を持った。