Kawabe and Takamori Burial Mounds

Kawabe-Takamori Kofun Group: Three Centuries of Keyhole Tombs in Usa

On a low terrace above the east bank of the Yakkan River in Usa City, Oita, six keyhole-shaped tombs and more than a hundred smaller mounds and moated burials sit in a quiet expanse of grass and pine. The earliest of them, Akatsuka, was raised at the close of the third century. The last, Tsurumi, dates to the middle of the sixth. Between these two points stretches an unbroken line of mortuary monuments built by what was very likely a single ruling lineage, the chieftains who controlled the Usa Plain for some three hundred years.

The grouping was designated a National Historic Site in March 1980 and is now preserved as the open-air park known as Usa Fudoki no Oka. The Oita Prefectural Museum of History stands at its centre, displaying the bronze mirrors, iron weapons and pottery recovered from the surrounding tombs. Together they make up one of the most informative kofun landscapes in Kyushu, second in scale only to the Saitobaru group in Miyazaki.

Six Tombs, One Lineage

The six large keyhole tombs are read as a generational sequence rather than as scattered burials. Their changing size and construction techniques map closely onto wider shifts in Kofun-period burial practice, which makes the site unusually useful for anyone trying to picture how regional power in early Japan grew, peaked and then settled into a more local rhythm.

Akatsuka, at the southern end of the museum's front lawn, is by far the most historically significant. The mound runs 57.5 metres in length, with a circular rear 36 metres across and 4.8 metres high. A surrounding moat eight to eleven metres wide once ringed it. When the tomb was excavated in 1921, archaeologists opened a single boxed stone coffin beneath the summit and recovered five bronze mirrors of the sankakubuchi shinjūkyō type (triangular-rimmed, deity-and-beast design), along with a tube-shaped jasper bead, fragments of an iron sword and an iron axe. Several of these mirrors share the same casting mould as mirrors found at Tsubai Ōtsukayama in Kyoto and Ishizukayama in Fukuoka, an indication that Akatsuka's occupant was tied directly into the gift networks of the early Yamato court. Akatsuka is widely treated as the oldest keyhole tomb in Kyushu.

Menga-hira, just south of Akatsuka, was built in the early-to-mid fourth century. Only the rounded rear of its 51-metre mound survives, which is why visitors often mistake it for a simple circular tumulus. Excavations in the 1970s and 1980s located two separate burials beneath the summit: a vertical-pit stone chamber holding a split-bamboo wooden coffin, and a stone cist alongside it. The vertical chamber yielded triangular-rimmed deity-and-beast mirrors, jasper bracelets, iron weapons and farming tools; the cist held the bones of a woman together with a slant-rimmed mirror and bracelet ornaments. The combined assemblage was designated an Important Cultural Property in August 2014.

Fukushōji, also called Kasugayama, is the largest mound in the group at roughly 80 metres long and the fourth-largest keyhole tomb in Oita Prefecture. Built in the early fifth century, it has never been excavated, and its interior remains an open question. Around its eastern and southern flanks lie a cluster of cist graves, pit burials and small mounds collectively known as the Fukushōji Burial Group, presumed to belong to retainers and family members of the chief buried in the central mound.

Kurumazaka and Kakubō, both fifth-century, continued the keyhole tradition at a more modest scale of 58 and 46 metres respectively. The interior of Kurumazaka contains a small adjacent circular mound called Jizōdō. Neither tomb has been opened.

Tsurumi closes the sequence in the mid-sixth century. At 31 metres it is the smallest of the six, with a strikingly short and wide front portion that is typical of late Kofun design. Its horizontal stone chamber is the only one in the group open to visitors. A short approach passage leads through two stepped sill stones into a domed chamber roofly two metres wide and 2.5 metres high, capped by a flat ceiling stone weighing about 1.3 tonnes. The walls were rebuilt to their original profile during conservation work in 1984 and 1985.

Why Akatsuka Matters

Of everything visible at Usa Fudoki no Oka, the Akatsuka mound carries the heaviest archaeological weight. The bronze mirrors recovered in 1921 belong to a small group of objects that scholars use to map the political reach of the nascent Yamato polity around the turn of the fourth century. The fact that mirrors cast from the very same mould have turned up at sites in Kyoto, Fukuoka and northern Kyushu suggests that they were not local products but ceremonial gifts distributed from a central authority to allied or subordinate chieftains across western Japan.

For a chieftain on the Usa Plain to receive such an object, and to be buried with five of them, implies a level of integration with the early Yamato network that is rare for Kyushu at this date. It is also part of why Akatsuka is often described as marking the moment when keyhole-shaped burial, a form developed in the Kinai region, first reached this corner of the island.

The Park Today

Usa Fudoki no Oka is laid out as a walkable history park. A network of paths links the six keyhole tombs and several smaller mounds, with explanatory panels in Japanese (and increasingly in English) at each major stop. Seasonal plantings of plum, cherry and irises soften the open ground; the early-spring cherry display is particularly well known among local visitors.

The Oita Prefectural Museum of History sits at the centre of the park. Inside, the permanent galleries focus on the Buddhist culture of the Usa and Kunisaki region (home to the great shrine of Usa Jingū and the Rokugō Manzan temple network), but the kofun gallery houses the artefacts excavated from the surrounding mounds, including the Akatsuka mirrors and the Important Cultural Property assemblage from Menga-hira. A full-scale reconstruction of the interior of Fuki-ji Hall (the oldest wooden building in Kyushu) anchors the Buddhist section.

Walking the park itself is free at any hour. Only the museum requires an admission ticket and observes set hours.

Around the Site

Usa Fudoki no Oka pairs naturally with two other destinations in the same district. The most obvious is Usa Jingū, head shrine of all Hachiman shrines in Japan and one of the most important religious sites in the country, located about ten minutes by car to the north. The kofun park provides the prehistoric backstory to the same ruling families who, several centuries later, would worship at and patronise Usa Jingū.

The Kunisaki Peninsula lies a short drive to the east. Its hidden valleys hold a remarkable concentration of stone Buddhist carvings and mountain temples, including the Kumano Magaibutsu rock-cut Buddhas, the Important Cultural Property statuary of Maki Ōdō, and the previously mentioned Fuki-ji. Anyone visiting the kofun group for half a day can comfortably combine it with one of these sites.

Closer to the park, the Komaki Pottery Kiln Site and the small museum at the Yokota Steel-Making Site offer a glimpse of the early industrial history of the same region. Lunch options in the immediate area are limited, so most visitors plan to eat in central Usa or near Usa Jingū before or after their walk.