One of southern Yamashiro’s largest keyhole mounds and the core of the Kutsukawa group. A chest-shaped sarcophagus was found in the rear mound, and the tomb is interpreted as that of a regional paramount chief.
Finds & research
The chest-shaped sarcophagus and its attached side compartments yielded seven bronze mirrors, armor, beads, and other objects. Numerous haniwa once lined the mound.
Official status & archaeological view
Official status
Designated a National Historic Site in 1979 as Kutsukawa Kurumazuka and Maruzuka Kofun, the site was renamed Kutsukawa Kofun Group in 2016 and extended in 2024.
Archaeological view
A three-tiered keyhole mound at Hirakawa Kurumazuka, Joyo. Its mound length is given as about 180m (Joyo City Museum of History and Folklore permanent exhibition; Nabunken site database, registered by the Joyo City Board of Education), about 175m in the city’s visitor guide and in Ritsumeikan University’s 2025 excavation report (based on trenches on the mound axis), and 184m in the Agency for Cultural Affairs’ 1979 designation record. Including its double moat it spans 272m. Built in the early 5th century, it has stone facing and haniwa rows.
Field notes
As investigation for site development continues, follow current Joyo City guidance and on-site visitor routes.