One of Isesaki’s Largest Kofun
Ofujiyama Kofun measures approximately 125 meters in total length, making it one of the largest keyhole-shaped burial mounds in Isesaki City.
It is believed to have been constructed between the early and middle parts of the 5th century. The front section originally extended toward the west-southwest, although part of it was later removed during the construction of the Ryomo Railway in the modern period.
Despite these changes, the mound still retains much of its impressive original form. Its considerable size can be appreciated even from a distance, giving visitors a sense of the power and status of the individual buried here.
Construction and Engineering Techniques
An archaeological investigation conducted by Gunma University in 1963 confirmed that the mound was built in three tiers.
The sloping surfaces were covered with fukiishi, or stone paving, while large cylindrical haniwa clay figures were arranged along the mound. A shield-shaped surrounding moat was also constructed around the kofun.
Including the surrounding moat, the entire complex originally extended for approximately 192 meters. These features demonstrate the sophisticated construction techniques of the Kofun period and the considerable resources and authority available to the people who commissioned the tomb.
Fuji Shrine on the Burial Mound
The summit of the rear section of the kofun is home to Fuji Shrine, also known as Fuji Sengen Shrine. The shrine continues to serve as a place of worship for the local community.
The presence of the shrine gives the ancient burial mound a unique character. Rather than existing solely as an archaeological monument, the site has remained connected with the lives and beliefs of local residents over many generations.
Beside the shrine stands the nagamochi-shaped stone sarcophagus, allowing visitors to see this rare archaeological object at close range.
The Rare Nagamochi-Shaped Stone Sarcophagus
One of the greatest highlights of Ofujiyama Kofun is its nagamochi-shaped stone sarcophagus, which was placed in the rear section of the mound.
Made of sandstone, the sarcophagus measures approximately 285 centimeters in length and 121 centimeters in width and weighs around 6.8 tons. It consists of several carefully shaped components, including a base stone, side stones, end stones, and a large lid.
Connections with the Yamato Region
This type of stone sarcophagus is particularly associated with the royal tombs of the Kinai region, the area surrounding present-day Nara and Osaka, during the 5th century.
Very few examples of this type have been identified in Gunma Prefecture. Ofujiyama Kofun is therefore an especially valuable example, comparable in importance to the stone sarcophagus at Ota Tenjinyama Kofun.
The form and manufacturing techniques of the sarcophagus closely resemble examples from the Kinai region. This has led researchers to suggest that craftsmen from the Kinai area may have traveled to eastern Japan to produce it.
The presence of such a distinctive coffin provides important archaeological evidence for considering the political and cultural connections between powerful local leaders in eastern Japan and the Yamato polity during the Kofun period.
Artifacts and Historical Significance
Other objects discovered at the kofun include small ritual replicas such as a stone imitation of a knife made from talc-like stone materials.
Some of the excavated artifacts are preserved and displayed at facilities such as the Akabori History and Folklore Museum, where visitors can learn more about burial customs and material culture during the Kofun period.
Ofujiyama Kofun was designated a Historic Site by Isesaki City in 1966. In 2001, its nagamochi-shaped stone sarcophagus was designated an Important Cultural Property of Gunma Prefecture, reflecting the archaeological importance of the site.
Why Visit Ofujiyama Kofun?
Ofujiyama Kofun is one of Isesaki’s most significant sites for experiencing the history of ancient eastern Japan. Visitors can see both the impressive scale of a 5th-century keyhole-shaped burial mound and the rare stone sarcophagus associated with elite tombs of the same period.
Walking across the mound provides an opportunity to imagine the political landscape of ancient Japan, when powerful local leaders in the eastern regions maintained connections with the Yamato political center.
For travelers interested in Japanese archaeology, ancient history, kofun, haniwa, and the origins of regional political power, Ofujiyama Kofun offers a fascinating glimpse into a period when monumental tombs reflected the status and influence of Japan’s early elites.