Osahozuka Kofun, Scallop-shaped kofun in Saitobaru, Saito, Japan

Osahozuka Kofun is a large scallop-shaped burial mound in Saitobaru, Saito, Miyazaki Prefecture. Its circular rear mound rises in three tiers to 19.1 m, with a short two-tiered front platform facing south-southeast. Two concentric moats, 15–25 m wide, encircle the mound but do not cross the front, forming an ear-ring shape. The mound measures 154.6 m today, with an original length estimated at 176 m.

Built in the first half of the 5th century, Osahozuka Kofun is a scallop-shaped mound 176 m long, the largest of its type in Japan. It was raised at the centre of the Saitobaru plateau, where six earlier chiefly burial lines had stood along the edges, and it appears to unite them. After it, tombs at Saitobaru shrank, and leadership in southern Kyushu shifted to the Yokose Kofun in Kagoshima. In 1895 the Imperial Household Ministry designated it a mausoleum reference site.

The scallop-shaped tomb reflects how ancient society marked social rank through burial practices and memorial design. Walking around it, you can sense how important position determined the scale and effort invested in a person's final resting place.

The mound is a fenced Imperial Household Agency reference tomb, so entry is normally not allowed; the grounds open only during the special worship on the second day of the Saitobaru Kofun Festival in early November. Otherwise view it from outside. Access is by Miyazaki Kotsu bus from Miyako City bus terminal to Saitobaru Kokogaku Hakubutsukan-mae, or to Saito Bus Center then taxi.

The iron armor and weapons were not found in the mound itself but in the adjacent Saitobaru No. 170 burial mound, a 47-meter round tomb, during digs in 1912 and again in 2004-2006. That mound also yielded the haniwa house and boat, both National Important Cultural Properties.