Jonozuka Tumulus, the largest of several ancient burial mounds (kofun) found in the Wakasa region, is a designated National Historic Site. It is one of nine confirmed keyhole-shaped mounds in the town of Wakasa and is located 50 meters east of Nishizuka Tumulus in the Wakibukuro area. The well-preserved mound is about 100 meters long in total, with the back circular part (south) and the front square part (north) being approximately 64 meters and 36 meters long, respectively. It measures about 60 meters across and stands 6 meters from the surface of the rice paddies that now surround it, though the square part is about one meter lower than the circular part.
This kofun was once surrounded by a moat, covered with stones, and decorated with ceremonial clay objects called haniwa. Analysis of the items discovered inside suggests that the tumulus dates to the early fifth century. Many historians believe that it may have been a tomb for the Kashiwade no Omi clan, who were officials responsible for supplying food from the Wakasa region to the imperial court. The area around Jonozuka Tumulus, including the former site of the moat, is now privately owned land used for farming.
