Imperial Household Agency: Oichi Tomb of Yamato Totohimomoso-hime
Location
Sakurai, Nara
Shape
Keyhole-shaped mound
Mound length
280 m
Period
Mid–late 3rd c.
Designation
IHA-managed tomb
IHA designation
Managed by the IHA (mound closed to the public)
Overview
A huge early keyhole mound central to debates over the emergence of the Yamato polity. Its date and relationship to Makimuku connect it to the Yamatai and Himiko debates. A second causeway across the moat was reported in 2026. It is part of the Makimuku Kofun Group.
Finds & research
The internal burial facility remains unexcavated. Investigations of the moat and perimeter have identified pottery, haniwa, and causeways, among other features. Views on its construction date vary, and the evidence does not establish a particular occupant.
Official status & archaeological view
Official status
The Imperial Household Agency designates and manages it as the Oichi Tomb of Yamato Totohimomoso-hime. Part of the area where the edge of the front section and the moat are presumed to lie was designated a National Historic Site, the "Hashihaka Kofun moat", in 2017.
Attribution (jitei): the Imperial Household Agency's determination of whose tomb it manages — separate from heritage designation.
Archaeological view
A c.280m keyhole mound (the Agency for Cultural Affairs’ database gives c.290m) at Hashinaka, Sakurai, at the southern edge of the Makimuku site. Its rear circle is about 160m across, the front about 130m wide, and the mound about 30m high. It is considered to have been built in the middle to latter half of the 3rd century and to be among the earliest large keyhole mounds. The occupant is unknown. Nara Prefecture’s heritage database notes that a good number of researchers regard it as the tomb of Himiko, who appears in the Wei Zhi account of Wa, but this is not established.
Field notes
The mound is closed as an Imperial mausoleum. View it from public roads and authorized areas, without entering the moat or managed precinct.