A designated historic site of the city where the remains of a castle built by the military commander Asahina who served under Imagawa and Takeda during the Warring States period are distributed over 2 ridges from a 180 m high summit. Presently, a stepped area and a flat area measuring about 55 m wide and 80 m long remain around the moat, main citadel, outer citadel and area around the outer citadel. It is said to be a "Nekoya" (literally root residence) type fort because it was made of earthen walls and a dry moat on the summit of a mountain with the castle of a daimyo at the foot.