History and Origins
Kōmorizuka Kofun is believed to have been constructed in the late Kofun period, during the second half of the 6th century. The mound measures approximately 100 meters in length. Inside its rounded rear section is a massive stone burial chamber built using the horizontal-entry method, in which a passage leads into the burial chamber.
The stone chamber measures 19.4 meters in total length. It is the largest of its kind in Okayama Prefecture and is regarded as the third-largest horizontal stone burial chamber in Japan.
The mound was formerly known as Kurohimezuka. According to local legend, it was the tomb of Kurohime, a woman from Kibi who was beloved by Emperor Nintoku. However, the burial mound dates to the late 6th century, more than a century after the traditionally estimated period of Emperor Nintoku in the 4th century. It is therefore now known as Kōmorizuka, meaning “Bat Mound,” a name said to derive from the many bats that once inhabited its stone chamber.
Archaeological Excavations and Discoveries
In 1967, an archaeological team from Okayama University and Okayama University of Science investigated the main burial chamber. In 1978, the Okayama Prefectural Board of Education carried out further excavations in the entrance passage.
The investigations revealed several types of burial containers, including a house-shaped stone coffin made from shell-bearing limestone, a ceramic coffin made from fired clay, and evidence of a wooden coffin. These discoveries suggest that the tomb may have accommodated multiple individuals.
Although the burial mound had been looted, numerous artifacts were recovered. They included Sue ware stoneware, Haji pottery, iron objects such as swords and horse equipment, small glass beads, faceted crystal beads, and gold rings. These finds provide valuable evidence of the burial customs, craftsmanship, and social status of the people who lived in the Kibi region during the Kofun period.
Distinctive Features of Kōmorizuka Kofun
The burial mound stands in Kamibayashi, Sōja City, and was constructed using the natural contours of a low hill. Its most remarkable feature is the 19.4-meter-long stone chamber, which opens toward the south from the rounded rear section of the mound.
The chamber contains a house-shaped stone coffin made from shell-bearing limestone quarried in what is now Ibara City. Excavations in 1978 also uncovered fragments of a turtle-shell-shaped ceramic coffin made from Haji pottery, as well as iron nails. These discoveries support the theory that more than one person was buried within the tomb.
Cultural Heritage and Designation
Kōmorizuka Kofun was designated a National Historic Site on February 15, 1968. More recently, on May 22, 2024, its excavated artifacts were designated Important Tangible Cultural Properties by Sōja City.
These designations recognize the site’s importance as a source of knowledge about the history and culture of ancient Kibi. The burial mound and its artifacts offer a valuable glimpse into the region’s powerful leaders, burial traditions, and connections with the wider society of ancient Japan.
Location and Nearby Attractions
Kōmorizuka Kofun is located in Sōja City, approximately a five-minute walk from Bitchū Kokubunji Temple. It is counted among Okayama Prefecture’s three great megalithic burial mounds, together with Yata Ōtsuka Kofun and Murozuka Kofun.
Its enormous stone chamber is particularly impressive and attracts history enthusiasts interested in ancient Japanese burial practices and archaeology. The surrounding natural setting adds to the appeal of a visit, making the site a rewarding stop for travelers exploring the historic landmarks of the Kibi region.
Discover the Ancient History of Kibi
Kōmorizuka Kofun is more than an ancient burial site. Its monumental stone chamber, surviving artifacts, and long history offer a tangible connection to the powerful leaders who shaped the Kibi region around 1,400 years ago.
When visiting Sōja City, consider combining a visit to the mound with nearby Bitchū Kokubunji Temple and other historic sites. Together, these landmarks reveal the rich archaeological and cultural heritage of Okayama Prefecture.