This is the largest ruins area from the Yayoi era (around 500 BC). The biggest characteristic is the collection of relics associated with the defense of the settlement, with about 2.5 km of outer bunkers and fences. In addition, as from excavation survey findings, pit dwellings, tall floor warehouses, observation towers, tombs, bronze ware, copper mirrors and the like have been discovered over an area of 36 hectares, making it a very important historical site which tells the story of the lives of people in ancient times.