A National Historic Site dated by its finds to the early 3rd century, the age of Himiko. Its front has been levelled, so the total length is unknown.
Finds & research
Finds include a four-beast mirror, copper bracelets, glass beads, jasper tubular beads, and magatama, collectively designated National Important Cultural Properties.
Two views on the occupant
Archaeological view
One of the earliest front-square/rear-square burials, at Terada Otani, Joyo. Its front has been levelled, while the rear survives at about 21m east–west by 23m north–south. A plank-built wooden coffin in the rear yielded copper bracelets, a bronze mirror, and beads.
Imperial Household Agency view
This is not an IHA mausoleum. It was designated a National Historic Site in 1989, and its finds are National Important Cultural Properties.
Field notes
The site is open as Shibagahara Kofun Park. Check current Joyo City History and Folklore Museum guidance for display information.