Kofun period
( or "roofing stone") were a means of covering burial chambers and burial mounds during the kofun period of Japan (). Stones collected from riverbeds were affixed to the slopes of raised kofun and other burial chambers. They are considered to have descended from forms used in Yayoi-period tumuli. They are common in the early and mid-Kofun periods, but most late Kofun-period tumuli do not have them.