This ancient tomb is characterized by a stone chamber made of beautifully cut and polished granite stacked perfectly with no gaps. It is a rectangular tumulus with sides of 40 meters that was built in the first half of the 7th century, and when compared to the Ishibutai tumulus, which was a rectangular tumulus made of granite in the early 7th century, you can see the progress in technology. Its characteristics are clearly seen in the monolithic ceiling, symmetrical stone chamber, and rain-cover grooves.