Iwayaato Kofun

The kofun was built on the plain at the south-western corner of the Iu plain in eastern Shimane. The surroundings are now rice paddies, most of the mound has been lost and the stone chamber is half destroyed. The shape of the mound is unclear; it is presumed to have been a round or square mound of about 20 m.

The burial facility is an Izumo-type stone-coffin-style chamber opening to the south-west. It was composed of a burial chamber, a passage and a forecourt, but only the burial chamber survives. The chamber measures 2 m in length, 3.3 m in width and 2.3 m in height. Its back wall and side walls are each a single slab, and the ceiling is also a single stone, worked into a house-shaped hipped form on both inner and outer faces. The passage was also built of a single slab, while the forecourt is of split-stone masonry. The form of the chamber is similar to that of Danbara Kofun.

Among the Izumo-type stone-coffin chambers found in eastern Izumo, this is a typical example with a clearly defined house-shaped roof, and it is noted as the largest of its kind. The chamber was looted, and its grave goods are not known.

Five or more human-figure haniwa were unearthed in the Meiji period during land clearance and are kept at the Tokyo National Museum (then the Imperial Museum). An excavation was carried out in the 1977 fiscal year by the Shimane Prefectural Board of Education, with a summary report in 1978.