Mano Kofun Cluster: A Late-Kofun Burial Ground on the Mano River
Roughly one hundred earthen mounds rise from the river terraces above the Mano River in Kashima Ward, Minamisoma City, where the northern Hamadōri coast of Fukushima meets the foothills of the Abukuma uplands. Most of them are small — gentle hummocks about ten metres across, easy to miss until one notices the wooden marker poles standing among the houses and field edges. Yet this is one of the largest tumulus clusters in the Tōhoku region, and from a single mound here came a Chinese-style ornament so rare that only a handful of comparable examples are known anywhere in Japan.
The cluster takes its name from the Mano River (Mano-gawa), which cuts an east–west valley through Kashima Ward on its way to the Pacific. The mounds were raised on the south bank, on a low terrace that gave the dead a view over the floodplain and, eventually, the sea. Together they form a sprawling necropolis some three kilometres across — a quiet record of a frontier society that took the burial customs of the central Japanese kingdom and adapted them to the northeastern edge of the archipelago.
Two Groups, Two Names — and a Single Designation
The site divides into two clusters about a kilometre apart. The eastern half lies in the Terauchi neighbourhood, in the localities of Hachimanbayashi and Ōyachi, and once held roughly eighty mounds; this is now known as the A district. The western half, in the Naganuma area of Koike, contained about twenty mounds and is designated the B district. Before 1979 these were treated as separate sites — the Hachimanbayashi, Ōyachi and Koike-bara groups respectively — but when the Agency for Cultural Affairs moved to register the area as a National Historic Site, the three were combined under the new collective name. The designation took effect on 24 October 1979 (Shōwa 54), and management of the site passed to the local municipality on 17 June 1981.
Roughly twenty-seven mounds have been formally investigated. Confirmation surveys in the mid-1970s identified twenty-four intact mounds and eleven partly damaged ones in the A district, and ten intact mounds with another five in a fragmentary state in the B district. The rest have been lost — to ploughing, road-building, or the steady creep of housing along the prefectural road that runs through Terauchi. What survives is a partial site, dotted across what is today a quietly inhabited rural landscape.
Small Mounds, Varied Chambers: How the Tombs Were Built
The cluster is overwhelmingly composed of small round burial mounds (en-pun), each about ten metres in diameter, but two larger forms stand out. The first is Mound No. 49, a round mound with a diameter of twenty-one metres. The second is Mound No. 20, a keyhole-shaped tomb (zenpō-kōen-fun) measuring 28.5 metres along its long axis and ringed by a shallow moat. Two such keyhole tombs and two enlarged round mounds occur within the cluster — a distribution typical of regional Late-Kofun cemeteries, where a small number of leaders' tombs preside over many subordinate burials.
Excavation has shown that the internal chambers vary considerably from mound to mound. Some hold a rekikaku, a chamber lined and filled with river pebbles; others a stone box coffin (hakoshiki sekkan) assembled from flat slabs; still others a modified vertical-shaft stone chamber, or — in the latest examples — a horizontal stone chamber (yokoana-shiki sekishitsu) of the kind that became standard across Japan during the sixth century. The variety is itself a clue to the cluster's span: construction began in the late fifth century and continued into the end of the sixth, with chamber forms shifting in step with the wider technical changes spreading from western Japan.
Why It Matters: Designation as a National Historic Site
The Agency for Cultural Affairs cites three reasons for the cluster's national importance. The first is its scale: this is one of the largest known burial grounds in the Tōhoku region and was already familiar to archaeologists by the prewar period. The second is its typological clarity. The combination of two keyhole tombs and a great many smaller round mounds is exactly the shape Late-Kofun cemeteries take in this part of the country, and the Mano cluster offers a textbook example of that regional pattern. The third reason is the grave goods.
From the various chambers excavators have recovered straight iron swords (chokutō), iron blades, horse harness fittings, and beads of stone and glass. Mound No. 49 produced a striking assemblage of stone replicas — miniature axes, sickles and tub-like vessels carved in soft talc — placed inside its pebble-filled chamber as substitutes for the real iron and wooden tools they imitate. Other mounds yielded bronze horse pendants (batō). And from a chamber set into the constricted waist of Mound No. 20 came the cluster's most celebrated find: a matched pair of gilt-bronze fish-shaped pendants known as kondō-sei sōgyo-hai.
The Gilt-Bronze Double-Fish Pendant
The double-fish pendant is an ornament of continental origin, derived from a Chinese tradition in which fish-shaped tokens hung from a belt as a mark of office. Such pendants are extremely rare in Japan; only a few comparable pieces are known nationwide, and during the Kofun period their distribution was almost entirely controlled by the Yamato court. Their appearance in a mound on the northeastern coast suggests that the person interred at Mound No. 20 was no ordinary local headman, but someone in direct relationship with the central polity hundreds of kilometres to the southwest.
The Mano pendants survive as two thin gilt-bronze sheets, each shaped into a stylised fish, joined by rivets through a pair of half-round mounting plates that once gripped a brocaded belt. Detailed reconstruction work carried out by Fukushima Prefecture's archaeological centre — based on the rivet positions and traces of textile preserved on the corroded metal — has shown that the pair was attached to the end of a fabric belt, almost certainly worn as a badge of rank in life before being committed to the grave. The pendants are designated an Important Cultural Property of Fukushima Prefecture.
Walking the Site Today
The Mano Kofun Cluster is not a fenced-off ruin but a working landscape with mounds embedded inside it. The A district sits just west of Otokoyama Hachiman Shrine in Terauchi, where the prefectural road runs past the foot of Mound No. 20. A wooden interpretive board explains the layout of the cluster as a whole, and individual mounds along the lane — Nos. 7, 8, 9, 11 and 12 among them — are marked with standing posts inscribed with their numbers and the 1979 designation date. Mound No. 20, the keyhole tomb with the moat, lies directly behind a bus stop and is the easiest to recognise: its trapezoidal silhouette still reads clearly against the surrounding rice fields.
Visitors should treat the site as a residential neighbourhood rather than an archaeological park. Several mounds lie inside the Ōyachi housing estate; some have been levelled, others remain among the gardens. Walking shoes, a printable map from Minamisoma City's tourism office, and a respectful distance from private property are all sensible. The actual finds — the swords, beads, horse trappings, and above all the pair of fish-shaped pendants — are held by the city and are not on continuous public display, but the Minamisoma City Museum across town devotes part of its standing exhibition to the region's Kofun-period archaeology and is the natural complement to a walk through the cluster itself.
What to See Nearby
Kashima Ward is the gentlest of Minamisoma's three former municipalities, with rice fields rolling down to the Pacific and the Abukuma highlands rising inland. Five minutes south by car, the roadside station Sedette Kashima offers local seafood and produce together with information panels on the 2011 disaster and its aftermath. The Minamisoma City Museum, about twenty minutes' drive south in the Higashigaoka Park area of Haranomachi Ward, presents the full archaeological story of the Hamadōri coast alongside displays on the Sōma Nomaoi — the thousand-year-old samurai horse festival held in late July and designated an Important Intangible Folk Cultural Property.
For visitors with a deeper interest in the region's tumuli, the Sakurai Kofun park in Haranomachi preserves a much earlier monument: a fourth-century keyhole-shaped mound that is among the northernmost of its kind. Paired with Mano, it offers a long view across the Kofun period as it unfolded on the northeastern frontier — from the first appearance of monumental tombs in the fourth century to the small clustered cemeteries that closed the era two centuries later.
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Q&A
- Can I actually walk among the burial mounds?
- Yes, the A district can be explored on foot from the prefectural road that runs through Terauchi. Several mounds are marked with wooden posts, and an interpretive panel near Mound No. 20 explains the wider cluster. The site is open ground rather than a managed park, so please stay on public lanes and avoid entering private gardens.
- How do I get there without a car?
- JR Jōban Line trains stop at Kashima Station. The A district is roughly twenty minutes on foot from the station, heading west along Route 49 toward Otokoyama Hachiman Shrine. The B district at Koike-Naganuma lies about a kilometre further west and is easier to combine with a rental cycle or a taxi.
- When were the tombs built, and by whom?
- Construction spans roughly the late fifth to the end of the sixth century, with most mounds belonging to the Late Kofun period. The people buried here were the local ruling families of what was then the northern edge of the Yamato sphere of influence, including at least one figure prominent enough to be granted a Chinese-style belt ornament from the central court.
- Where can I see the gilt-bronze fish pendants?
- The pair is curated by the city of Minamisoma and is shown in occasional special exhibitions rather than on permanent display. The Minamisoma City Museum is the best starting point for inquiries; check the museum's current exhibition schedule before you travel if seeing the originals is essential to your visit.
- Is photography allowed on site?
- Photographing the mounds from public roads is fine. Some mounds stand on private land, so look for the standing posts and stay on the lane side of any boundary. Drone photography requires advance permission from the city's cultural properties section.
Basic Information
| Name | Mano Kofun Cluster (真野古墳群, Mano Kofun-gun) |
|---|---|
| Location | Terauchi (Hachimanbayashi, Ōyachi) and Koike (Naganuma), Kashima Ward, Minamisoma City, Fukushima Prefecture |
| Designation | National Historic Site (史跡), designated 24 October 1979 |
| Managing Body | Minamisoma City (since 17 June 1981) |
| Composition | Approximately 80 mounds in the A district and 20 in the B district; 27 mounds investigated; mainly small round mounds of about 10 m diameter, with two keyhole-shaped tombs (longest 28.5 m) and two larger round mounds (largest 21 m diameter) |
| Period | Late Kofun period, late 5th to end of 6th century, with some earlier Middle-Kofun elements |
| Chamber Types | Pebble-filled chamber (rekikaku), box-shaped stone coffin, modified vertical-shaft stone chamber, horizontal stone chamber |
| Notable Finds | Pair of gilt-bronze double-fish pendants (Mound No. 20), stone replicas of axes, sickles and vessels (Mound No. 49), straight iron swords, horse harness fittings, bronze horse pendants, beads |
| Access | About 20 minutes on foot from JR Jōban Line Kashima Station; the related Minamisoma City Museum is about 20 minutes by car in Haranomachi Ward |
| Admission | Free; the site is open countryside with no fixed opening hours |
References
- 真野古墳群 — 文化遺産オンライン (Cultural Heritage Online, National Institute of Informatics)
- https://bunka.nii.ac.jp/heritages/detail/137814
- 国指定文化財等データベース (Agency for Cultural Affairs Database)
- https://kunishitei.bunka.go.jp/
- 鹿島区の文化財 — 南相馬市公式ウェブサイト (Cultural Properties of Kashima Ward, Minamisoma City)
- https://www.city.minamisoma.lg.jp/tourist/tourist_attractions/historic/culturalproperty/6853.html
- 真野古墳群A地区20号墳出土金銅製双魚佩の鋲と組立について — 福島県文化財センター白河館「まほろん」紀要
- https://www.fcp.or.jp/mahoron/kiyou/2001_35_1.htm
- 真野古墳群 — Wikipedia 日本語版
- https://ja.wikipedia.org/wiki/真野古墳群
Last verified: 2026.05.16