Nanatsu-mori Kofun Group: Ancient Burial Mounds on a Kyushu Plateau
Nestled on the Sugō Plateau in western Taketa City, Oita Prefecture, the Nanatsu-mori Kofun Group (七ツ森古墳群) is a collection of ancient burial mounds dating back to the 4th century—the early Kofun period of Japanese history. Designated as a National Historic Site in 1959, this archaeological treasure offers visitors a rare chance to walk among well-preserved keyhole-shaped tombs that once served as the final resting places of powerful local rulers.
Though the name "Nanatsu-mori" (Seven Forests) suggests there were originally seven tumuli, only four remain today: two round mounds (enpun) and two distinctive keyhole-shaped mounds (zenpō-kōen-fun). Each autumn, the gentle slopes surrounding these ancient tombs are transformed into a breathtaking sea of approximately 200,000 red spider lilies (higanbana), creating one of the most evocative landscapes in all of Kyushu—where ancient history and natural beauty converge in a single unforgettable scene.
A Window into Early Kofun Period Kyushu
The Nanatsu-mori Kofun Group holds immense archaeological significance as one of the oldest Kinai-style keyhole-shaped tumuli in the Hōhi region (the area spanning present-day Oita and Kumamoto Prefectures). The presence of keyhole-shaped mounds this far south in Kyushu provides valuable evidence of the spread of the Yamato court's cultural influence from the Kinai heartland (modern-day Nara and Osaka) to the distant provinces during the 4th century.
The first archaeological investigation was conducted in 1924 (Taishō 13), when researchers excavated the two keyhole-shaped mounds (designated as Kofun B and Kofun C). The findings were remarkable: six bronze mirrors, magatama (curved jade beads), jasper stone bracelets (hekigyoku-sei kushiro), and deer-antler-handled knives (rokukaku-sō tōsu) were unearthed. Among the most notable discoveries were the jasper bracelets, which had been intentionally shattered and scattered near the remains—a rare funerary practice in Kyushu that strongly suggests cultural ties to the Kinai region.
Although the six bronze mirrors recovered during the 1924 excavation have since been lost, scholars believe they may have included triangular-rimmed deity-and-beast mirrors (sankaku-buchi shinjū-kyō), a type closely associated with the Yamato court. This would place the Nanatsu-mori tombs alongside other significant early Kofun sites in Oita, such as the Akatsuka Kofun in Usa City.
Exploring the Four Remaining Tombs
Each of the four surviving mounds has its own distinct character and archaeological story to tell.
Kofun A: The Western Round Mound
Located at the western edge of the group, Kofun A is a round mound (enpun) measuring approximately 20 meters in diameter and 4 meters in height. Excavation revealed a small boat-shaped stone coffin (funagata sekkan) inside. The diminutive size of the stone pillow within the coffin suggests that the person buried here was likely an infant, offering a poignant glimpse into the life and mortality of the ruling class during this era.
Kofun B: The Largest Keyhole Mound
Kofun B is the most impressive of the four mounds, stretching 51 meters in total length. The rear circular portion measures 28 meters in diameter and stands 6 meters high, while the front rectangular section is 8 meters wide and 3 meters tall. Its elongated "handle" shape—known as egagami-shiki (mirror-handle style)—is characteristic of early Kofun period tombs. A combination-style stone coffin (kumiawase-shiki sekkan) discovered at the center of the rear mound contained the extended remains of an adult male.
Kofun C: The Second Keyhole Mound
Similar in form to Kofun B, Kofun C is another egagami-style keyhole-shaped mound with its front section facing west. Together with Kofun B, it yielded the significant trove of grave goods during the 1924 excavation. A second investigation in 1954 (Shōwa 29) confirmed the presence of a box-type combination stone coffin in the rear mound, along with tubular beads (kudatama), small beads (kodama), and other artifacts.
Kofun D: The Eastern Round Mound
The fourth and easternmost mound, Kofun D, is another round mound. Together with the other three tombs, it helps paint a picture of a burial complex used by a local clan of considerable power and influence during the formative years of the Japanese state.
Why Was It Designated a National Historic Site?
The Nanatsu-mori Kofun Group was designated as a National Historic Site (Kuni Shitei Shiseki) on May 13, 1959, with the City of Taketa appointed as its management body in 1960. The designation was based on several factors of national importance.
First, the keyhole-shaped mounds are considered among the earliest of their kind in the upper Ōno River basin, providing critical evidence for understanding how central Yamato culture spread to inland Kyushu. Second, the mound forms have been remarkably well preserved, retaining their original dimensions and shapes to a high degree. Third, the grave goods—particularly the jasper bracelets and bronze mirrors—demonstrate direct connections to Kinai-region burial customs, making these tombs invaluable for studying political and cultural networks in early Japan. Finally, the presence of archaic-style stone coffins in the round mounds adds to the scholarly understanding of regional burial practices during this period.
A Carpet of 200,000 Red Spider Lilies
While the ancient tombs are the historical heart of this site, many visitors are first drawn here by the spectacular display of red spider lilies (Lycoris radiata) that blankets the grounds each September. Approximately 200,000 of these vivid crimson flowers bloom across a 600-tsubo (roughly 2,000 square meters) area surrounding the ancient mounds, creating a scene of almost surreal beauty.
The story behind this floral display is one of community dedication. By the mid-1950s, the kofun grounds had fallen into disrepair. Local residents began clearing and maintaining the site, and over the decades, wild spider lilies gradually colonized the area, spreading naturally across the gently rolling terrain. Today, the combination of ancient burial mounds rising from a sea of crimson flowers has become one of Taketa's most iconic autumn images.
The annual Nanatsu-mori Higanbana Festival is typically held in mid-September, with peak bloom usually occurring around September 20th. In August, visitors can also enjoy orange-colored Lycoris sanguinea (kitsune-no-kamisori), a related species that blooms a month earlier.
The site also gained national recognition when it was featured as a backdrop for reminiscence scenes in director Nobuhiko Ōbayashi's 2007 film "22-sai no Wakare" (Farewell at Twenty-Two).
Surrounding Attractions
The Nanatsu-mori Kofun Group is ideally situated for combining with other Taketa City highlights to create a full day of sightseeing.
Just about 2 kilometers further along Route 57, the Roadside Station Sugō (Michi-no-Eki Sugō) offers local produce, fresh vegetables, and the famous fried chicken from Marufuku, a beloved local restaurant with over 50 years of history. The surrounding Sugō Plateau is known for its highland vegetables and sweet corn, particularly during summer.
In the heart of Taketa City, roughly 15 minutes by car, stands the magnificent Oka Castle Ruins (Oka-jō Ato), a National Historic Site and one of Japan's Top 100 Castles. The towering stone walls of this mountain fortress inspired composer Rentarō Taki to write "Kōjō no Tsuki" (The Moon over the Ruined Castle), one of Japan's most beloved classical melodies. The castle offers panoramic views of the Kujū Mountains and Mount Aso.
The historic castle town of Taketa itself is a charming area for strolling, with well-preserved samurai residences, the Rentarō Taki Memorial Hall, and atmospheric stone-paved lanes. Nearby, Nagayu Onsen is famous for its exceptional natural carbonated hot springs, which are among the finest in Japan and a perfect way to conclude a day of cultural exploration.
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Q＆A
- Is there an admission fee to visit the Nanatsu-mori Kofun Group?
- No, admission is free. The site is open and accessible year-round. During the spider lily season in September, local vendors sometimes set up a small stall selling fresh vegetables, but there is no entrance charge.
- When is the best time to visit?
- The most popular time is mid- to late September, when the red spider lilies are in full bloom (typically peaking around September 20th). However, the ancient mounds themselves can be appreciated at any time of year. In August, orange Lycoris sanguinea flowers bloom, and spring and winter offer quieter visits with the mounds set against changing seasonal scenery.
- Can I climb on or enter the burial mounds?
- No. As a designated National Historic Site, the mounds are protected by law. Visitors can walk around the mounds and view them from close proximity, but climbing on them or attempting to enter any chambers is prohibited.
- How do I get to the Nanatsu-mori Kofun Group?
- The site is located directly along National Route 57, making it very easy to find by car. From JR Bungo-Taketa Station, it is approximately 10–15 minutes by car heading toward Kumamoto. The Roadside Station Sugō is about 1–2 km further along Route 57 and serves as a convenient landmark. There is limited parking available at the site.
- Are there English-language signs or guides at the site?
- Signage at the site is primarily in Japanese. It is recommended to research the history beforehand or visit with a local guide. The nearby Taketa City Historical and Cultural Museum (Yūgaku-kan) provides additional context about the region's archaeological heritage.
Basic Information
| Official Name | Nanatsu-mori Kofun Group (七ツ森古墳群 / ななつもりこふんぐん) |
|---|---|
| Designation | National Historic Site (designated May 13, 1959) |
| Period | Early Kofun period (4th century CE) |
| Composition | 2 keyhole-shaped tumuli (zenpō-kōen-fun), 2 round tumuli (enpun) — 4 of the original 7 mounds survive |
| Largest Mound | Kofun B: total length 51 m, rear circle diameter 28 m, height 6 m |
| Location | Toue, Taketa City, Oita Prefecture 878-0013, Japan (along National Route 57) |
| Managing Body | Taketa City |
| Admission | Free |
| Access | Approximately 10–15 minutes by car from JR Bungo-Taketa Station (JR Hōhi Main Line) |
| Contact | Taketa City Commerce and Tourism Division — TEL: 0974-63-4807 |
References
- 七ツ森古墳群 — 文化遺産オンライン
- https://bunka.nii.ac.jp/heritages/detail/206763
- Nanatsumori Kofun Cluster — Wikipedia (English)
- https://en.wikipedia.org/wiki/Nanatsumori_Kofun_Cluster
- 七ツ森古墳群 — Wikipedia (Japanese)
- https://ja.wikipedia.org/wiki/%E4%B8%83%E3%83%84%E6%A3%AE%E5%8F%A4%E5%A2%B3%E7%BE%A4
- 七ツ森古墳群 | おおいた文化財ずかん
- https://oita-digitalzukan.jp/cultural_property/%E4%B8%83%E3%83%84%E6%A3%AE%E5%8F%A4%E5%A2%B3%E7%BE%A4/
- 国指定史跡 七ツ森古墳群 | たけ旅（竹田市観光ツーリズム協会）
- https://taketa.guide/spots/detail/c5a7188b-bfc6-4f41-9aec-05dbbf04cedd
- 七ッ森古墳群（国指定史跡）| 竹田市公式サイト
- https://www.city.taketa.oita.jp/bunka_rekishi_kanko/bunkazai/siteibunkazai/9213.html
- 七ツ森古墳の彼岸花 | 大分県観光情報公式サイト
- https://www.visit-oita.jp/spots/detail/6039
Last verified: 2026.03.03