The Onobaru Site was a production plant of the Jomon earthenware during the late Jomon Era (about 4,000-3,000 years ago). The Jomon earthenware was made with the clay formed by the weathered pyroclastic deposit from the Aso Volcano, and they were traded via the Ariake Sea.
The Onobaru Site Museum, located in the Ariake Culture Hall, exhibits the artifacts unearthed during the construction of its main hall and the soil layers seen in its surrounding area. Visitors can learn about the people's lifestyle during the Jomon Era.