Wada-jo Castle was built on a hill overlooking the surrounding area. The main building of the castle was 50 meters square on one side and surrounded by high embankments.
Seven medieval castles have been identified in Wada-dani Valley, where the Wada-jo Castle Ruins are located. These castles were built at the edge of hills with a view or at the entrance to valleys. Invaders to the Wada-dani Valley were constantly monitored by the castles on both sides of the valley, with any suspicious activity triggering an attack, cutting off any escape routes. The fighting style of ninja villages that were well defended and difficult for enemies to attack can be observed from the Wada-jo Castle Ruins and other castle ruins in the valley.