Asamachi Yamaguchi remains (Asamachi Yamaokuchi Ichiki) investigated 22 circular mounds during Showa 57 - 58 along with the maintenance of the prefectural field (Hojo). It is confirmed that the grave structure that the peculiar tomb of the Munakata area (the hole digging the ground to build a rock / stone room) is deep and the ceiling stone is nearly buried in the ground.