| Location | Osaka Pref. |
|---|---|
| Shape | Keyhole-shaped mound |
| Mound length | 181 m |
| Period | Early 6th c. |
The largest keyhole burial mound in the Yodo River basin (181m). The three-tiered mound measures 100m in rear-circle diameter (~11m high) and 120m in front-section width (~9m high), surrounded by a double moat. Designated a National Historic Site in 2011. A prime example of the significant gap between IHA designation and archaeological consensus: the IHA-designated Ota Chausuyama dates to the mid-5th century, whereas Imashiroduka's haniwa typology points to the early 6th century, close to Emperor Keitai's death in 531 CE.
Multiple excavations by Takatsuki City Board of Education (2000s onward); continued since National Historic Site designation in 2011. Finds include pottery of Omi/Hokuriku style, Korean-influenced Sue ware, and diverse figural haniwa (~80 types: houses, canopies, shields, roosters, dogs, horses, shamanesses, wrestlers). Evidence of mound collapse linked to the 536 CE earthquake has also been confirmed. The adjacent Imashiroduka Ancient History Museum displays finds and multimedia exhibits; a reconstructed haniwa ceremonial site with ~80 life-sized replicas is installed in the park.
Fully open to the public as a free park, featuring Japan's first reconstructed haniwa ceremonial site with approximately 80 life-sized replica haniwa. The adjacent Imashiroduka Ancient History Museum displays excavated artifacts and multimedia exhibits. Every spring, the "Imashiroduka Ancient History Festival" is held. Walking paths traverse the mound, and the summit of the rear circle offers panoramic views over the Yodo River basin. Nearest stations: JR Settsu-Tonda or Hankyu Tonda, ~15 min walk.