A late-period mound preserved in Sakurabasama Historic Park, Yasu City. Its chamber still holds an intact house-shaped sarcophagus of Aso pink stone shipped from Kumamoto — first-class evidence that royal-grade coffin culture reached Omi. It sits at the foot of Mt. Oiwa, famed for its bronze-bell hoards.
Finds & research
Corridor-type chamber (~14.3m, the largest in Shiga) with an intact Aso pink-stone sarcophagus. Finds: gold thread, lamellar armor, glass and silver beads, horse trappings, weapons.
Two views on the occupant
Archaeological view
A round mound ~30m across and 8m high, built in the early-to-mid 6th century. Its corridor-type chamber, ~14.3m long, is the largest surviving in Shiga, and holds an intact monolithic house-shaped sarcophagus of Aso pink stone (welded tuff from Kumamoto's Uto Peninsula), 2.6m long — the prefecture's largest. Hauling the coffin from Kyushu to Lake Biwa attests to the occupant's power and royal connections. Finds include gold thread, lamellar armor, beads, horse gear, and weapons. The adjacent Maruyama Kofun holds a slightly earlier Aso-stone coffin.
Imperial Household Agency view
Not designated by the IHA. Part of the National Historic Site "Oiwayama Kofun Group" (1941; expanded to eight mounds in 1985), managed by Yasu City.
Field notes
Bus or walk from JR Yasu Station. Within Sakurabasama Historic Park (9:00–17:00, closed Mondays, free); the chamber interior is normally closed for conservation, with special autumn openings. Combine with Maruyama Kofun and the Doutaku (bronze bell) Museum.