Tanba's largest keyhole mound, lying in the eastern Sasayama basin in Tanba-Sasayama City. Meiji-era drawings of its buried armory conjure a warrior king. Managed by the IHA as a reference site, the mound itself is off-limits, but the view across the water-filled moat is imposing.
Finds & research
The 1896 investigation found numerous swords and armor pieces in a pit-style stone chamber. Its chest-style sarcophagus remains unopened. A 2004 IHA survey also identified haniwa and Sue ware.
Two views on the occupant
Archaeological view
A keyhole mound 140m long as visible, or 158m when its submerged foot is reconstructed, with a shield-shaped moat and outer belt. It was built in the mid-5th century. Local researchers opened a pit-style stone chamber in 1896 and found a chest-style sarcophagus with many weapons and armor pieces. Contemporary drawings record the arrangement; removed objects are held by the Kyoto University Museum. The sarcophagus was never opened. Tanba-Sasayama City describes a chieftain of regional ruler rank as the usual interpretation.
Imperial Household Agency view
The IHA manages it as the Kumobe Mausoleum Reference Site; Tanba-Sasayama City lists the designation date as 30 March 1900. A tradition associates it with Tanba-no-Michinushi, but the archaeological date of the mid-5th century does not identify an occupant. The mound is closed to entry.
Field notes
As a mausoleum reference site, the mound is closed; view it from outside. The Hyogo Prefectural Museum of Archaeology notes that no parking is available nearby and displays a reconstruction of the chamber and coffin based on the excavation drawings.