Enfun Ōtsuka Kofun

Enfun Ōtsuka Kofun, also called Minano Ōtsuka Kofun, is a large circular burial mound in Minano, Chichibu District, Saitama Prefecture, Japan. It stands on the lowest terrace of the right bank of the Arakawa River, on the western foothills of Mount Minobu, and has been designated a Prefectural Historic Site of Saitama since 1958.

The mound is round, measuring approximately 33 metres in diameter and 7 metres high, though alternative figures of 18 metres in diameter and 5 metres high are also given. Its exterior retains stone facing made from rounded river stones, but no pottery figures have been found. A surrounding ditch is about 4 metres wide and 1 metre deep.

Inside is a two-passage horizontal stone chamber opening toward the south-southwest. It extends 9.1 metres in total; the main chamber is 5 metres long, 3.15 metres wide at the centre, 2.9 metres wide at the rear wall, and 2.9 metres high. Built of schist, it has projecting wall stones forming a domed ceiling, a floor paved with fist-sized river stones, and surviving entrance stones. The chamber was looted, so its grave goods are not known, and no archaeological excavation has been carried out.

An Edo-period gazetteer described the already-open chamber under the name “氷ノ雨塚.” The mound is generally dated by its form to the second quarter of the 7th century, near the end of the Kofun period. Entry to the stone chamber is now restricted.

Enfun Ōtsuka Kofun is a megalithic mound (tumulus with integral stones) in Japan. A typological estimate: 250 CE to 650 CE. No English Wikipedia article exists for it; the full text below is the Japanese article "円墳大塚古墳", shown in the original language.