The shape of the mausoleums of Okimi also changed from a keyhole to a square after the construction of Mise Maruyama-kofun Tumulus, Umeyama-kofun Tumulus and Taishi Nishiyama-kofun Tumulus, all of which are believed to have been built in the second half of the sixth century.
大王陵としても6世紀後半に造営されたとみられる見瀬丸山古墳か梅山古墳、または太子西山古墳を最後に前方後円墳から方墳へと変わった。