This small square tomb was built on the southern slope near the tip of a ridge extending east from Mt. Nijo, on the western edge of the Nara Basin. It was discovered in 1983 (Showa 58) when soil was collected during the renovation of a reservoir (large pond), and an excavation survey was conducted thereafter.
The tomb is square, measuring approximately 7.6 meters on each side. Two rows of stone paving can be seen on the surface of the mound, and a trench runs around the three sides of the mound except for the south side. The burial facility is a horizontal-entry stone coffin, with the main axis of the coffin running east-west and opening to the south. A slab of stones is assembled on top of the bottom stone, and a ceiling stone is placed on top of that. The inside dimensions of the stone coffin are 158 cm long, 60 cm wide, and 70 cm high, and the opening is 40 cm wide and 50 cm high. The stone is made of tuff from Mt. Nijo, and the bottom stone and northern stone are unfinished house-shaped stone sarcophagus lid stones. It is also believed that there was a passage-like facility at the entrance to the stone coffin. As it was looted, no grave goods have been found inside the stone coffin, but Sue ware and Haji ware have been found near the front of the coffin.
The tomb is believed to have been built in the late 7th century, towards the end of the Kofun period. It is unclear who was buried there, but one theory is that it is the true grave of Prince Otsu, son of the 40th Emperor Tenmu (the current grave is designated as being on the top of Mt. Nijo).
The tomb area was designated a Nara Prefecture historic site in 1987 (Showa 62). Currently, access to the stone coffin is restricted.