Kaide Castle was the residence of Nakakoji, a country gentleman who was active during the Warring States period.
The wealthy landowners and samurai in the Otomune Nishioka region were well-known throughout the country for their participation in the country-wide uprising aimed at achieving autonomous regional governance.
The castle remains a valuable example of the role of country gentlemen’s residences as a base for their activities. Excavations at Kaide Castle revealed that it was a typical structure with a square residence measuring about 70 meters on each side, surrounded by a 6.5-meter-wide, 2-meter-high earthen wall and a moat about 8 meters wide and 1 meter deep.
The main entrance, which is estimated to be in the southwest, has a distinctive protrusion to the south.
Large post and beam structures measuring more than 3 ken (9 meters) in the east, west, north, and south, as well as well-like stone structures and remains of burned soil and charcoal that are believed to be stoves, were discovered inside the castle.
The earthen wall on the west side and the earthen wall at the southeast corner have been preserved (partially restored) thanks to the efforts of local landowners and others.
The castle remains a valuable historical monument that preserves the medieval history of the region and serves as a base for the country-wide uprising.