An important investigated example of a burial facility predating standardized keyhole tombs. Sakurai City dates it to the mid-3rd century. It is part of the Makimuku Kofun Group.
Finds & research
The stone-enclosed wooden chamber yielded pictorial-band same-direction-type deity-and-beast mirrors, an inner-flower mirror, bronze and iron arrowheads, iron swords, iron agricultural tools and other tools, decorated double-rimmed jars, and small round-bottomed vessels, among others. No triangular-rimmed deity-and-beast mirror was identified.
Official status & archaeological view
Official status
A component of the National Historic Site Makimuku Kofun Group (designated in 2006 together with Makimuku Ishizuka; Makimuku Yazuka and Katsuyama were added in February 2026).
Archaeological view
An approximately 80m keyhole mound at Hashinaka, Sakurai, built in the mid-3rd century. The rear has at least two tiers and the front one; it is the only Makimuku-type keyhole mound within the Makimuku site with stone facing. Its central burial facility is a stone-enclosed wooden chamber holding a boat-shaped coffin. A horizontal stone chamber was added beside it in a later period.
Field notes
Part of the mound and the moat-like features on its north to east sides have been restored and opened to the public (Sakurai City). A car park and an arbor stand on adjacent land.