With regard to the surrounding moat, some portions of the approximately 10-meter-wide surrounding moat and the 10-to-20-meter-wide outer levee have been found in the excavation research of portions of the square front and rounded rear.
周濠は、前方部と後円部の一部分の発掘調査から、幅10m前後の周濠と幅数十m前後の外堤の一部が見つかっている。