As mentioned earlier, the area of Honmaru, that had a convex shape, was surrounded by mud walls built on the stonewalls, and watchtowers were built on each of the four corners of the square shaped main area.
本丸は、先にもいったように凸型をしており、石垣上部の土壁が囲い正方形部の四隅には御矢倉が建てられた。