The Ueno Narahara Shioji Forest: A Primeval Riverside Wilderness in the Heart of Gunma
Deep in the mountains of western Gunma Prefecture, along the upper reaches of the Kanna River, lies a living relic of Japan's ancient forests. The Ueno Narahara Shioji Forest (Ueno Narahara no Shioji-rin) is a primeval grove of Japanese flowering ash trees that has stood undisturbed for nearly three centuries. Hidden in the steep, mist-laden valleys of the Hosoozawa stream, this forest is one of the last remaining examples of the riverside ashwood that once flourished across mountainous Japan.
Designated a National Natural Monument and Natural Protection Area in 1969, the site holds a special distinction. There are only 23 Natural Protection Areas (Tennen Hogo Kuiki) in all of Japan—the highest tier of natural monument protection, reserved for the most representative and richly endowed natural environments. Of those 23, only two exist on the Kanto mainland: the famous Oze marshlands and this quiet, almost forgotten ashwood in the village of Ueno.
A Forest Untouched Since the Edo Period
What makes this forest extraordinary is its history of non-intervention. The Shioji groves of Kitazawa have not been logged since the Horeki era (1751–1763)—over 270 years ago. While the surrounding mountains of Ueno Village were once heavily worked for timber and the village itself developed a thriving forestry industry, the stand along the Hosoozawa stream was left alone. The result is a forest of remarkable maturity, where Shioji trees soar to heights of around 35 meters, and the oldest specimens reach trunk diameters of up to 115 centimeters at chest height. Many of the trees are believed to be around 200 years old or more.
The strictly protected core covers 55.55 hectares, lying between approximately 920 and 1,060 meters in altitude on the right bank of the Hosoozawa, a tributary deep within the Kitazawa valley. The wider catchment—290.19 hectares—was further designated as a Gunma Prefecture Natural Environment Conservation Special Area in 1975, and the Forestry Agency added it to its register of Plant Community Protection Forests in 1993. Few places in Japan are wrapped in so many overlapping layers of conservation.
Why This Forest Was Designated
The Shioji (Fraxinus platypoda), known in English as the Japanese flowering ash, is a deciduous broadleaf tree of the olive family that thrives in moist mountain stream environments on the Pacific side of Japan. Ueno Village sits very near the northern limit of its natural range. Forests where Shioji dominates the canopy have almost entirely vanished from the Japanese landscape, surviving today only as scattered, narrow strips along remote streams.
When the Agency for Cultural Affairs sought to safeguard Japan's most representative natural forests during the rapid economic expansion of the 1960s, the Ueno Narahara Shioji Forest was singled out as the country's leading example of an undisturbed riverside ash community. The designation, made on 25 July 1969, was both a recognition of its botanical rarity and an urgent measure to ensure that at least one such ecosystem would survive into the future. Alongside Shioji, the forest harbors Japanese beech (Inubuna), horse chestnut (Tochi), Japanese magnolia (Hou), walnut (Onigurumi), and the spectacular heart-shaped leaves of Katsura.
Highlights and What to See
Reaching the Shioji Forest is itself part of the experience. The route follows the Kitazawa Gorge upstream, threading past clear pools, rocky cascades, and the tributaries of Hagisawa, Hosoozawa, and Tochihirasawa. The trail also passes the remains of a former settlement and the site of the old Kitazawa branch school—a poignant reminder of the families who once lived deep in this valley during the heyday of forestry in the early 20th century.
When you finally arrive in the primeval grove, the atmosphere shifts. The tall, straight Shioji trunks rise like cathedral columns; older trees display the characteristic vertical fissures of their bark. Sunlight filters through the high canopy in shifting patterns, and the sound of the Hosoozawa stream is constant. Spring and early summer bring fresh green leaves and wildflowers along the banks; autumn turns the broadleaves into a soft mosaic of gold and amber. The recommended visiting season runs from June through November, when the trail is generally passable.
Around the Forest: Exploring Ueno Village
Ueno Village is the smallest community by population in Gunma Prefecture, tucked into the Chichibu mountains where Gunma meets Saitama and Nagano. Despite its remoteness, it offers a remarkable concentration of attractions. The Fujido Cave, a 2.2-kilometer limestone cave designated a Gunma Prefecture Natural Monument, is among the largest in eastern Japan and can be toured along an illuminated 40-minute route. Just above the cave stretches the Ueno Sky Bridge, a pedestrian suspension bridge with sweeping views over the forested valley.
Other nearby points of interest include Tengu-iwa, a rocky outcrop with a popular hiking route to the summit, Otome-no-taki (the Maiden's Waterfall), the Former Kurosawa Family Residence—an Edo-period merchant house designated an Important Cultural Property—and Mahoba-no-mori, an outdoor activity park with forest adventure courses and zip lines. For weary hikers, the village's hot spring facility, Shiojino-yu, offers a chance to soak among the same mountain forests.
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Q&A
- What exactly is a "Natural Protection Area" (Tennen Hogo Kuiki)?
- It is the highest category of National Natural Monument in Japan, given to areas that represent particularly rich and well-preserved natural environments. Only 23 such areas exist nationwide, and the Ueno Narahara Shioji Forest is one of only two on the Kanto mainland, the other being Oze.
- How old are the trees in this forest?
- The forest has not been logged since the Horeki era (1751–1763), so many of the dominant Shioji trees are estimated to be around 200 years old or more. The largest specimens reach about 35 meters in height and 115 centimeters in trunk diameter.
- When is the best time of year to visit?
- Visits are generally recommended between June and November. Early summer offers fresh greenery and wildflowers along the stream, while autumn brings beautiful broadleaf colors. Winter access is not advised due to snow and difficult mountain conditions.
- How do I get there from Tokyo?
- The most practical option is by car: take the Joshin-etsu Expressway to Shimonita Interchange, then drive about 30 kilometers (around 35 minutes) into Ueno Village via Prefectural Route 45 through the Yunosawa Tunnel. Public transport requires the Joshin Electric Railway to Shimonita Station and a shared village taxi to the Uenomura Fureai-kan, followed by a long mountain walk to reach the forest itself.
- Can I enter the protected core area freely?
- There is a marked trail through the Kitazawa Gorge that allows visitors to experience the forest, but the area is a strictly protected National Natural Monument. Visitors are asked to stay on the trail, take all litter home, and avoid disturbing plants, wildlife, or the streambed. Joining a local guided walk is highly recommended.
Basic Information
| Name | The Ueno Narahara Shioji Forest (Ueno Narahara no Shioji-rin) |
|---|---|
| Designation | National Natural Monument / Natural Protection Area (Tennen Hogo Kuiki) |
| Designation Date | 25 July 1969 (Showa 44) |
| Location | Kitazawa, Narahara, Ueno-mura, Tano-gun, Gunma Prefecture |
| Designated Area | 55.55 hectares (core) / 290.19 hectares (prefectural conservation zone) |
| Altitude | Approximately 920 m – 1,060 m |
| Principal Species | Shioji (Fraxinus platypoda, Japanese flowering ash), with Inubuna, Tochi, Hou, Onigurumi, and Katsura |
| Maximum Tree Height | Approximately 35 m |
| Maximum Trunk Diameter | Approximately 115 cm at breast height |
| Access | From Shimonita IC, 30 km / 35 min by car via Prefectural Route 45. Best visited June–November. |
References
- Cultural Heritage Online — Ueno Narahara no Shioji-rin
- https://bunka.nii.ac.jp/heritages/detail/209780
- Agency for Cultural Affairs — National Cultural Properties Database
- https://kunishitei.bunka.go.jp/bsys/maindetails/401/00004092
- Uenomura Kanko Navi — Shioji Primeval Forest (National Natural Monument)
- https://uenomura-kankonavi.jp/spot/spot-1861/
- Ueno Village Official Site — Kitazawa Gorge and Shioji Primeval Forest Route
- http://www.uenomura.jp/tourism/play/shioji.html
- Gunma Prefecture Green Promotion Committee — Ueno Narahara no Shioji-rin
- https://www.g-sinrin.jp/kyozyukoboku/上野楢原のシオジ林/
- Wikipedia — Ueno Narahara no Shioji-rin
- https://ja.wikipedia.org/wiki/上野楢原のシオジ林
Last verified: 2026.05.15