A large keyhole mound (203m, 4th largest in the Mozu group) in Mozuhonmachi, Kita-ku, Sakai City. The three-tiered mound, 18.3m high at the rear circle, faces west and has a single projection on the south side of its waist. One moat is visible today, but a second, outer moat once encircled it and is preserved underground. Access to the mound itself is restricted as an IHA reference site. Located only about 500m southeast of Daisen Kofun, the two giant mounds together form the dominant landscape of the Mozu plateau. One of the 49 constituent monuments of the "Mozu-Furuichi Kofun Group" UNESCO WHS (2019).
Finds & research
The mound is built in three tiers, and cylindrical haniwa set edge to edge were recovered from the first terrace. On and around the projection (tsukuridashi) a wide range of figural haniwa came to light — notably an enclosure-shaped (kakoigata) haniwa among the largest known, and a house-shaped haniwa whose form recalls shrine architecture. Miniature vessels, underfired Sue ware and clay models of fish and baskets were also found, evidence of rites performed on the projection. The burial facility and grave goods remain uninvestigated under IHA management.
Official status & archaeological view
Official status
The Imperial Household Agency manages it as the "Mozu Ryobo Sankochi" (reference site) (Sakai City; 2009 government written answer). A reference site is a category the IHA manages like a mausoleum because it could possibly be one; it does not establish the occupant. It is administered by the IHA Archives and Mausolea Department, and access to the mound is restricted. The moat around the mound (Gobyo Pond) was added to the National Historic Site "Mozu Kofun Group" in 2018 as the "Gobyoyama Kofun inner moat".
Attribution (jitei): the Imperial Household Agency's determination of whose tomb it manages — separate from heritage designation.
Archaeological view
The occupant is archaeologically unknown. It is the 4th largest in the Mozu area after Daisen, Kamiishizu Misanzai and Haze Nisanzai (Agency for Cultural Affairs). Dated to the middle of the Middle Kofun period (first half of the 5th century). It is presumed to have a close relationship with Daisen Kofun.
Field notes
About a four-minute walk southeast of JR Mozu Station. The front and rear sections can be observed from the moat-side path; convenient to combine with nearby Daisen Kofun and the Sakai City Museum.