This is a keyhole-shaped tumulus tomb measuring 107.5 meters in length, 44 meters in width at the “triangle” portion of the tomb, and 54.5 meters in diameter at the “circle” portion of the tomb. This two-level burial mound is surrounded by a dry moat. Based on the shape, the tumulus is believed to date back to the early 5th century and is registered as a National Historic Site. At present, the area is maintained as a park where visitors can relax and tour the tumulus perimeter at their own pace.