A group of kofun (tumulus) occupying the whole of a small island overlooking the Naruto Strait. Numerous small-scale stone chambers were made here by piling up unworked rocks and are thought to be the graves of Ama chieftains given that the main grave goods were fishing tackle. Chlorite-schist, characteristic of Nushima Island, was used for the stone rods, which shows the involvement of the Ama, whose livelihood has been the sea.