In the present day in Minato City, there are nine sites that have been recognized as Kofun tombs. Among them, Shibamaruyama Kofun, the group of circular tombs and the Kofun tombs excluding Kamezuka that has not been confirmed as a Kofun tomb, had not been investigated archaeologically. In recent years, investigations of Haniwa (clay image) fragments collected on site at Shibamaruyama Kofun and the group of circular tombs, as well as detailed test-pit digs carried out at Kamezuka have revealed new insights. Instances have increased of similar Haniwa being found in the excavated remains, and it could be said that the time has come for a reevaluation of the Kofun tombs in the region.