Photo: Charlie fong, Wikimedia Commons (CC BY-SA 4.0)
Mt. Asama Hiking Guide: Maekakeyama and Kurofuyama Trails, Volcanic Alert Levels, and Access (2026)
Mt. Asama is an active volcano on the Nagano–Gunma border near Karuizawa. Based on the Japan Meteorological Agency and Komoro City, this guide covers where you can hike at each alert level, the mandatory climbing plan, the two main trails, parking, and buses.
Based on the Japan Meteorological Agency (JMA), Komoro City, the Komoro tourism bureau, and Nagano Prefecture, checked October 24, 2026. Mt. Asama is an active volcano and the alert level can change at any time. Check the JMA and Komoro City right before you go.
Overview
Mt. Asama (2,568 m) stands on the border of Nagano and Gunma prefectures, northwest of Karuizawa. It is one of the 100 Famous Mountains of Japan and an active volcano. On May 22, 2026, the JMA lowered its Volcanic Alert Level from 2 (Do not approach the crater) to 1 (Potential for increased activity), and Komoro City eased the trail restrictions so hikers can again reach Maekakeyama (2,524 m).
In its October 23, 2026 commentary, the JMA keeps the level at 1 but notes that volcanic earthquakes have increased slightly since late September and asks hikers to check the latest volcano information.
First: Alert Levels and Where You Can Go
Even at Level 1, the JMA warns that a very small eruption affecting the area within 500 m of the summit crater is possible. Follow the local government's instructions, stay out of dangerous areas, and watch for sudden ash emissions and volcanic gas.
Komoro City's hiking information sets out which trails are open at each level:
- Level 1: the Kazankan course (Asama Sanso – Ichi-no-torii – Ni-no-torii – Kazankan – Yunotaira junction – Sai-no-kawara junction – Maekakeyama), and the Kurofu course to Maekakeyama via the J-band (for strong hikers)
- Level 2: Maekakeyama is closed. You can walk the area of Kazankan, Kusasuberi, Kurofuyama, Jakotsudake, Sennindake, and the J-band
- Level 3: the Kazankan course is open only from Tengu Onsen Asama Sanso to Ichi-no-torii; the Kurofu course is closed
- Levels 4 and 5: no entry
Komoro City has designated the area within 4 km of the crater a restricted zone under the Disaster Countermeasures Basic Act, allowing entry only on the trails according to the alert level. If the JMA raises the level, the city announces restrictions by public broadcast and other means; follow them.
The true summit, Kamayama, is next to the crater and has no public trail. Maekakeyama is as far as hikers can go.
A Climbing Plan Is Mandatory
Under Nagano Prefecture's mountain safety ordinance, you must submit a climbing plan (tozan keikakusho) for designated trails, and both the Kurofu and Kazankan courses are designated trails. Forms are available at each trailhead.
The Two Main Courses
| Maekakeyama course | Kurofuyama course | |
|---|---|---|
| Trailhead | Tengu Onsen Asama Sanso | Kurumazaka Pass |
| Difficulty (Komoro tourism bureau) | Intermediate | Beginner to intermediate |
| Time (same source) | About 7 hours | About 3–4 hours |
| Public transport | Limited | Easy |
| Best for | Seeing the crater up close | Views of Mt. Asama; first-timers |
Nagano Prefecture's 2026 mountain grading rates them as follows:
| Route | Fitness (1–10) | Technical (A–E) | Course time | Distance | Ascent |
|---|---|---|---|---|---|
| Kurofuyama (from Kurumazaka Pass) | 2 | A | 3.6 h | 5.2 km | 510 m |
| Maekakeyama (from Kurumazaka Pass) | 4 | B | 8.7 h | 12.1 km | 1,300 m |
| Maekakeyama (from Asama Tozanguchi) | 4 | B | 9.3 h | 21.8 km | 1,480 m |
The last row starts at the Asama Tozanguchi bus stop (about 1,200 m). Starting at Tengu Onsen Asama Sanso is shorter.
Maekakeyama Course (Kazankan Course)
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From Tengu Onsen Asama Sanso, the trail climbs through forest to Kazankan and Sai-no-kawara, then up to Maekakeyama. Above the treeline you cross bare gravel slopes with the steaming crater close by.
- Kazankan (2.3 km from the crater): staffed by Komoro City, offering hiking advice. Closed every Monday and Tuesday (its phone does not answer on closed days). It has a bio-toilet (a donation of about 300 yen is requested) and lends helmets free of charge in limited numbers, so bring your own if you can.
- Shelters: about 500 m from the crater, at 2.3 km (Kazankan), and at 3 km (Yarigasaya on the Kurofu course).
- Water: we could not confirm a water source from official information, so carry plenty.
Parking at Tengu Onsen Asama Sanso
According to the Komoro tourism bureau:
- 500 yen per car, from 5 a.m. (1,000 yen if you park before 5 a.m.)
- About 300 spaces (lots 1 to 3), with toilets
- Sleeping in your car, even a nap, requires paying the campsite fee
- Never park on the road
Kurofuyama Course
This course climbs Kurofuyama (2,404 m), the highest point of Mt. Asama's outer crater rim, from Kurumazaka Pass via Yarigasaya and Tomi-no-kashira. Tomi-no-kashira is billed as the highlight of the course.
- Takamine Kogen Visitor Center: open 8:30–17:00, with a café and shop
- Parking: free at the visitor center, Takamine Kogen Hotel, and Takamine Mountain Park. When full, do not park on forest roads or road shoulders; it blocks the buses
- Komoro City warns of falls in the snow season caused by crampons catching on rocks
The "outer rim course" beyond Kurofuyama continues via Jakotsudake, Sennindake, and the J-band to Maekakeyama and is for strong hikers. Komoro City reported a hiker injured in a fall on the ridge above the J-band in June 2024.
Access
Maekakeyama course (Tengu Onsen Asama Sanso)
- By car: about 25 minutes from Komoro Station (Shinano Railway) or from Komoro IC on the Joshin-etsu Expressway
- By bus: JR Bus Kanto from Komoro Station to the "Asama Tozanguchi" stop, then about 70 minutes on foot to the trailhead
Kurofuyama course (Kurumazaka Pass)
- By car: about 30 minutes from Komoro IC
- By bus: JR Bus Kanto's Takamine Kogen line from Komoro Station to "Kurumazaka-toge / Takamine Kogen Hotel-mae" (about 35 minutes); the trail starts right there
- Direct highway buses run from Busta Shinjuku in Tokyo to Saku and Komoro Station. Komoro City lists the local bus (Sakudaira Station – Komoro Station – Takamine Kogen) at two round trips a day (updated March 2025)
Timetables and fares change; check JR Bus Kanto before you go.
Season and Clothing
Komoro City notes that Kurofuyama and snowshoeing are popular in winter, but this is a mountain over 2,000 m: spring and autumn are cold, and crampons and other winter gear may be needed when there is snow. The Komoro tourism bureau records first snowfalls on October 17, 2020, October 20, 2021, and October 25, 2022, and strong, cold winds on the ridge in mid-October. In late October especially, be ready for ice and cold.
- Boots with good grip for volcanic gravel and scree
- Rain gear, warm layers, and gloves (strong wind can chill you fast)
- A headlamp: Komoro City reports several rescues of hikers lost after dark without a light
- A helmet (lent at Kazankan, but numbers are limited)
- A map app and a power bank
- A bear bell: Komoro City reported a bear sighting near Kazankan in July 2025. See bear safety in Japan
Before and After
- Tengu Onsen Asama Sanso (Maekakeyama trailhead) offers day-use bathing after your hike (check its site for prices and hours)
- Takamine Onsen and Takamine Kogen Hotel near the Kurofuyama trailhead also offer day-use bathing
- The Komoro tourism bureau also recommends Kaikoen, the Komoro Castle ruins park
Not Confirmed
- Whether there is a water source on the Maekakeyama course
- An official course time to Maekakeyama from Asama Sanso (Nagano's grading only gives times from Asama Tozanguchi and Kurumazaka Pass)
- Current bus timetables and fares
- Day-use bath prices and hours at Tengu Onsen Asama Sanso
Summary
- The alert level was lowered to 1 on May 22, 2026, reopening the trail to Maekakeyama; it was still Level 1 on October 23, 2026, with a slight rise in earthquakes since late September
- The open area changes with the alert level; check the JMA and Komoro City before you go
- Both main courses are designated trails, so a climbing plan is mandatory
- First-timers: Kurofuyama, easy by bus and less demanding. To see the crater: Maekakeyama
- Asama Sanso parking: 500 yen, from 5 a.m., about 300 cars
See also: 22 Hyakumeizan day hikes from Tokyo · Japan hiking rules: the basics