This way of thinking toward an octagonal burial mound was changed due to the continuous discovery of the Isezuka-kofun Tumulus (located in Fujioka City, Gunma Prefecture), the Mitsuya-kofun Tumulus (located in Yoshioka-cho, Gunma Prefecture), and the Kyozuka-kofun Tumulus (located in Ichinomiya-cho, Higashi Yashiro County, Yamanashi Prefecture [present day Fuefuki City]) after the discovery of the Inarizuka-kofun Tumulus in the Eastern Japan.
東日本では稲荷塚古墳の発見に続き、群馬県藤岡市の伊勢塚古墳、群馬県吉岡町の三津屋古墳、山梨県東八代郡一宮町(山梨県)（現笛吹市）の経塚古墳と発見が続いたため八角墳に対する考え方を変える事となった。