The principal mound of the Otsukayama group, a National Historic Site whose mounds were built from the late 5th to early 6th century. It was designated in 1956.
Finds & research
The moat and part of a possible outer moat have been identified. The central burial facility and full grave assemblage remain unknown.
Official status & archaeological view
Official status
It was designated a National Historic Site on 28 December 1956 as part of the Otsukayama Kofun Group.
Archaeological view
A keyhole mound at Kawai. Its surviving mound measures 197m (Kawai Town and Nara Prefecture; the 1956 designation text gave a main-axis length of about 190m). Kawai Town’s 2024 survey found the buried northern mound edge about 3m beyond the visible edge, establishing an original length over 200m. Its preliminary 2025 survey found the southern edge and suggested that the total may be about 4m longer still. It is the centerpiece of the eight-mound Otsukayama group and among the largest in the Nara basin for its period.