A 1999 survey found a koguchi (castle entrance) that was closest to the castle's inner citadel, which revealed a massive koguchi zone where the castle path had bent at least five times from the first gate. This unusually large space, which was around half the size of the inner citadel itself, constituted part of the castle's elaborate defensive design. The foundation stones that probably belonged to the gate and the area around the gate had been paved with gravel, while the stone mounds outside the entrance had been stacked using large boulders, making this entrance likely to be the inner citadel's main entrance.