Kusahaka Kofun, also known as Karato Kofun, is an ancient square burial mound located in Tani, Sakurai City, Nara Prefecture. Designated a National Historic Site of Japan in 1974, it is considered an important archaeological monument from the final phase of the Kofun period, when elaborate burial structures were built for powerful individuals and ruling families.
The tomb stands along the eastern edge of the Abe Hills, on the left bank of the Terakawa River. Although archaeological excavations have not yet been carried out, its dimensions and sophisticated stone chamber make it a valuable site for understanding the burial customs and social hierarchy of ancient Japan.
Kusahaka Kofun is located in the southern part of the Nara Basin, where it was constructed on hilly terrain. The mound is approximately square, with its northwestern and southeastern sides slightly longer than the other sides. It measures about 27 meters along its longer sides and 21 meters along its shorter sides.
The top of the mound has been leveled, giving it the form of a truncated pyramid. The exterior was covered with paving stones, but no haniwa clay figures have been confirmed at the site. A level area also surrounds the mound, forming part of its overall layout.
The tomb’s size and construction suggest that it was built for a powerful local clan leader or another high-ranking individual. Its distinctive form and substantial burial chamber make it an important example of the monumental tombs constructed during the late Kofun period.
The burial facility is a horizontal stone chamber with a double-entrance arrangement, opening toward the southeast. It measures 13.16 meters in total length and is built from enormous granite blocks.
The main burial chamber measures 4.44 meters long, 2.71 meters wide, and 2 meters high. The passage leading from the chamber to the entrance measures 8.72 meters long, 1.9 meters wide, and 1.5 meters high.
The rear wall is constructed with one large stone per course, while the side walls use two stones per course. Plaster was applied between the stones to seal the joints, and traces of this material remain visible in places. The combination of massive stone blocks and carefully finished joints demonstrates the considerable technical skill of the builders.
At the center of the main burial chamber stands a large, hollowed-out house-shaped stone sarcophagus made from Tatsuyama stone. This stone, quarried in the Kakogawa River basin in Hyogo Prefecture, was widely valued for its suitability for sculptural and architectural work.
The sarcophagus measures approximately 2.4 meters long, 1.5 meters wide, and 1 meter high, with an interior depth of about 0.5 meters. Its lid features eight rope-handling projections arranged in four pairs: one pair at each end and two pairs along the sides. Shallow carved recesses are also visible on the interior.
The sarcophagus is notably large in comparison with the stone chamber surrounding it. This has led to the theory that the sarcophagus was placed in position before the chamber and the burial mound were completed. If correct, this construction sequence would offer valuable insight into the planning and building methods used for elite burials in ancient Japan.
Kusahaka Kofun is generally dated to the middle of the seventh century, during the final phase of the Kofun period. Some researchers suggest an earlier date in the first half of the seventh century.
During this era, influential aristocratic clans played important roles in the political life of the emerging Japanese state. The surrounding Abe Hills contain other monumental tombs, including Tanikubi Kofun and Monjuin Nishi Kofun, placing Kusahaka Kofun within a wider landscape of elite burials.
Remains of large buildings have also been discovered at nearby archaeological sites. These findings suggest a possible connection with the ancient Abe clan, although the identity of the person buried at Kusahaka Kofun has not been established.
Kusahaka Kofun was officially designated a National Historic Site of Japan on June 18, 1974. Its importance lies in its unusual square shape, enormous stone chamber, and substantial sarcophagus, all of which provide clues to the funerary practices and social organization of the late Kofun period.
Because the tomb has not yet been excavated, many aspects of its history remain unknown. Further archaeological research may help clarify its construction date, the identity of its occupant, and its relationship with other ancient sites in the Abe Hills.
Kusahaka Kofun is a significant destination for travelers interested in ancient Japanese history and archaeology. Its massive stone chamber and carefully constructed sarcophagus offer a glimpse into the advanced building techniques and elaborate burial customs of the period.
Although much remains to be discovered, the tomb stands as a lasting reminder of the powerful families who shaped the Nara region more than a thousand years ago.