Kobushi-dake (甲武信ヶ岳, 2,475 m) sits at the meeting point of Yamanashi, Saitama, and Nagano — its name is read as a contraction of the three old provincial names: Ko (甲, Kai / Yamanashi), Bu (武, Musashi / Saitama), and Shin (信, Shinano / Nagano). The peak is a watershed point for three river systems — the Chikumagawa (千曲川, which becomes the Shinanogawa in Niigata), the Arakawa (荒川), and the Fuefukigawa (笛吹川, which joins to form the Fujikawa). On a clear day the summit gives one of the broadest panoramas in the Oku-Chichibu range, looking out to Mount Fuji, Yatsugatake, and the Southern Alps. Most hikers reach it from the Yamanashi side near Nishizawa Keikoku or from the Nagano side at Mokidaira.
Why Fukada Chose Kobushi-dake
Kobushi-dake is one of the hundred peaks in Kyuya Fukada's Nihon Hyakumeizan. Fukada's book is ordered roughly geographically from north to south rather than as a ranking, and Kobushi-dake falls between Kumotori-yama and Kinpu-san in that sequence. What drew Fukada to the mountain was its position at the convergence of three old provinces and its role as a watershed source feeding rivers that run to opposite coasts of Honshu. It is a quiet, deeply forested peak at the heart of the Oku-Chichibu range, and that combination of geographical significance and unspoiled woodland is central to its place among the hundred.
The Mountain
| Detail | Value |
|---|---|
| Elevation | 2,475 m (8,120 ft) |
| Prefectures | Yamanashi / Saitama / Nagano (triple border) |
| Name | Read as Ko (甲) + Bu (武) + Shin (信) |
| Watershed | Source point of the Chikumagawa, Arakawa, and Fuefukigawa |
| Summit note | No triangulation point; neighbouring Sanpo-zan (~2,483 m) is slightly higher |
| Book order | Roughly north-to-south, not a ranking |
| Typical season | Late April – November |
On a clear day the summit reportedly takes in as many as 43 of the hundred famous mountains, with Mount Fuji to the south, Yatsugatake to the west, and both the Southern and Northern Alps on the horizon — an unusually open outlook for a peak buried this deep in forest.
The Routes
There are two distinct standard approaches, from opposite sides of the watershed.
Yamanashi side: Nishizawa Keikoku → Tokuchan-shindo → Summit
Grade: Challenging (usually an overnight)
From the Nishizawa Keikoku-iriguchi trailhead, the climb branches onto a ridge trail — the Tokuchan-shindo (徳ちゃん新道, Towatari ridge) or the Chikamaru-shindo (近丸新道) — and ascends over Tokusa-yama (木賊山) to the summit. The scenic Nishizawa gorge boardwalk is a separate, mostly flat loop excursion and is not part of this ascent. The round trip runs roughly 15.8 km and around 9.5 hours of walking, with substantial cumulative climbing, so most hikers do it as an overnight using Kobushi-goya.
Nagano side: Mokidaira → Chikumagawa source trail → Summit
Grade: Moderate (day-hikeable)
From the Mokidaira (毛木平) trailhead, the route follows the Chikumagawa source trail (千曲川源流遊歩道) past the headwaters of the river up to the summit. The round trip is roughly 15 km and around 7 hours, and it is the gentler of the two — the more practical choice for a single-day climb.
Getting There
To the Yamanashi side (Nishizawa Keikoku):
Take the Chuo Line to Yamanashi-shi or Enzan (Shiozan) Station, then a bus to the "Nishizawa Keikoku-iriguchi" stop (~60 minutes), operated by Yamanashi Kotsu / Fuefuki Kanko. A rental car via Route 140 is the other option.
To the Saitama side (Chichibu):
Access is via the Chichibu Railway (秩父鉄道) to Mitsumineguchi Station, then a bus toward Tochimoto. Note that the Seibu line terminates at Seibu-Chichibu Station; you transfer to the Chichibu Railway to reach Mitsumineguchi. The Saitama side is a long, remote traverse rather than a short summit route, so plan accordingly.
Mountain Huts
Kobushi-goya (甲武信小屋): A staffed hut just below the summit and the standard overnight and water point for the climb. It is generally open from late April to 30 November, with capacity around 150. One night with two meals is roughly 10,000 yen, and a tent pitch around 1,500 yen. Reservations are required.
Flora and Wildlife
Asiatic black bears (ツキノワグマ): Present throughout the Chichibu-Tama-Kai range. This is the black bear of Honshu, not the brown bear of Hokkaido. Carry a bear bell and make noise on quiet stretches. An active bear-caution advisory was posted for the national park as of late May 2026 — check current notices before you go.
Forest and flowers: The area is dense primeval forest of cometsuga and shirabiso (コメツガ / シラビソ), part of the Kobushi Biosphere Reserve recognised by UNESCO. Rhododendron (シャクナゲ) blooms abundantly through the summit forest in June.
Seasonal Guide
Late April – June: The hut season opens and the trails clear, though snow can linger on the upper slopes early on. Rhododendron flowers around the summit in June.
July – August: The main hiking season. Lower elevations are humid; the summit stays comparatively cool.
September – October: Crisp, stable weather and autumn colour in the surrounding forest — many hikers' favourite window.
November onward: The hut closes at the end of November and the upper trail turns to a winter route requiring proper snow gear and experience.
Practical Tips for Foreign Visitors
Plan the Yamanashi side as an overnight. The Nishizawa-side climb is long and steep enough that a same-day return is hard for most; booking Kobushi-goya in advance makes it far more comfortable.
For a day hike, start from Nagano. The Mokidaira route along the Chikumagawa source is shorter and gentler and is the realistic single-day option.
Get the rail line right on the Saitama side. Mitsumineguchi is on the Chichibu Railway, not the Seibu line — you transfer at Seibu-Chichibu. Buses onward to the trailhead are infrequent, so check timetables before travelling.
Carry your own water and treatment. Kobushi-goya is the reliable water point; don't count on untreated stream water along the climb.
Frequently Asked Questions
Can Kobushi-dake be done as a day hike, or do you need to stay overnight?
It depends on which side you climb. The Nagano (Mokidaira) route along the Chikumagawa source trail is roughly 15 km and around 7 hours, and is the realistic single-day option. The Yamanashi (Nishizawa) side runs roughly 15.8 km and around 9.5 hours with substantial climbing, so most hikers do it as an overnight using Kobushi-goya.
Do I need a reservation for the mountain hut?
Yes. Reservations are required at Kobushi-goya, the staffed hut just below the summit. It is generally open from late April to 30 November, with capacity around 150. One night with two meals is roughly 10,000 yen, and a tent pitch around 1,500 yen.
Can I reach the trailheads without a car?
Yes, on the Yamanashi side. Take the Chuo Line to Yamanashi-shi or Enzan (Shiozan) Station, then a bus to the "Nishizawa Keikoku-iriguchi" stop (about 60 minutes), operated by Yamanashi Kotsu / Fuefuki Kanko. A rental car via Route 140 is the alternative. On the Saitama side, access is via the Chichibu Railway to Mitsumineguchi Station — you transfer at Seibu-Chichibu, since the Seibu line does not run there — and buses onward are infrequent.
When is the best season, and how long does snow linger?
September and October bring crisp, stable weather and autumn colour, making that many hikers' favourite window. The hut season runs late April to November, but snow can linger on the upper slopes early in the season, and rhododendron flowers around the summit in June. After the hut closes at the end of November, the upper trail becomes a winter route requiring proper snow gear and experience.
Are there bears, and what should I do?
Asiatic black bears live throughout the Chichibu-Tama-Kai range — this is the black bear of Honshu, not the brown bear of Hokkaido. Carry a bear bell and make noise on quiet stretches. An active bear-caution advisory was posted for the national park as of late May 2026, so check current notices before you go.
This guide is part of the Japan's 100 Famous Mountains: Complete Hyakumeizan Guide series.
