tiers of stones. Excavations were conducted in 1994–1997. The burial facility is a horizontal stone chamber orientated to the south. The total length of the burial chamber including the entry passage was 10.7 meters. Inside were six Haji pottery coffins (2 tortoiseshell-shaped, 4 gabled house-shaped) and nailed wooden coffins. Grave goods were similar to that of the Sada-Higashi Kofun, and date the construction to the end of the Kofun period, around the first half of the 7th century, and immediately following the Sada-Higashi Kofun. Sada-Kita Kofun The Sada-Kita Kofun is located about 70 meters north of the Sada-Higashi Kofun and Sada-Nishi Kofun on the southern slope of a hill overhanging the east bank of the Nakatsui River. The mound is rectangular, measuring 25.3 meters from north to south and 21 meters from east to west, and is surrounded by three tiers of outer guard stones; the middle tier measuring 1.8 meters contains the opening of the burial chamber. Excavations were conducted from 1990 to 1993. The burial facility is a horizontal stone chamber orientated to the south. The chamber is two-tiered and is paved with flat pebbles. Inside were four Haji pottery coffins (2 tortoiseshell-shaped, 2 gabled house-shaped), wooden coffins with nails (1.8m in length, 0.6m in width), and an additional burial urn (medicine pot-shaped Sue ware). Grave goods included small ball and cut-glass beads, weapons (iron swords, arrowheads), copper bowls, ax-shaped iron products, and Sue ware (bowls, lids, and flat jars). Sue pottery jars have also been unearthed on both sides of the opening. The tumulus is estimated to have been built around the middle of the 7th century, at the end of the Kofun period. Ōya No.1 Kofun The Ōya No.1 Kofun was built on the southern slope of a hill overhanging the west bank of the Nakatsui River. The mound is rectangular, measuring 13.1 meters east–west, 9.8 meters north–south, and 3.8 meters high. It is surrounded by three tiers of stone guards, and two tiers of stones (18–22 meters in length) in front of the mound, giving the front view the appearance of a five-tier construction.The top of the mound is covered with flat stones.E xcavations were conducted in 1988 and from 1992 to 1994. The burial facility is a horizontal stone chamber with two sleeves and opens in the south-southeast direction. The burial chamber was made from five megalithic stones, one each on the back wall,