Besides playing an important role in defending the area to the west of Sunpu Castle, Tanaka Castle, where Tokugawa Ieyasu was said to have stayed often whenever he came for falconry, was made up of 4 concentric circles with the inner citadel in the center, a characteristic that is also very unusual in Japan. The current Nishimashizu Elementary School sits on the former site of the inner citadel but during the late Edo period, the buildings including the inner citadel watchtower were relocated and restored on the ruins of the garden of the feudal lord Tanaka. Today, it is a beautiful garden where you can take a leisurely stroll.It is one of the cultural properties of Japan Heritage.