Mt. Otensho

Mt. Otensho (大天井岳, 2,922 m), on the border of Omachi, Azumino and Matsumoto in Nagano, is one of the 200 Famous Japanese Mountains.
It is the highest peak of the Jonen Range, and standing at the hub of the “Omote-Ginza” traverse that links Mt. Tsubakuro to Mt. Yari, it offers a grand view stretching to the Yari–Hotaka peaks and the Tateyama and Ushiro-Tateyama ranges. Daitenso lodge sits just below the summit and Otensho Hütte lies on the ridge; the classic plan is a two-day climb from Nakabusa Onsen via Mt. Tsubakuro, an advanced route with long ridge walking and rocky sections.
For public transport to the trailhead, a regular bus runs from Hotaka Station on the JR Oito Line to Nakabusa Onsen (Tsubakuro trailhead), and an overnight bus from Takebashi in Tokyo also serves it.

The trailhead is the Tsubakuro trailhead at Nakabusa Onsen (about 1,450 m). The standard route is Nakabusa Onsen → Kassen Ridge → Enzanso lodge (overnight) → Odori-no-Atama → Mt. Otensho (Daitenso), with a total ascent time of about 7–8 hours. It cannot be done as a day trip and is an advanced route that assumes one night on the mountain at Enzanso or Daitenso. Kassen Ridge is a steady steep climb on a well-maintained path, and beyond Enzanso it becomes a ridge stroll above the tree line.
On the ridge there are three mountain lodges — Enzanso, Daitenso and Otensho Hütte — serving as bases for lodging, rest and emergencies. The best season is early July to early October, after the snow melts; outside it there is snow and ice, and the ridge is exposed to strong wind and sudden weather changes. Always check the latest trail, residual-snow and lodge-operation conditions in advance.

*Last checked: June 6, 2026

How to access the trailhead

1. [Outbound] Hotaka Station → Nakabusa Onsen (Tsubakuro trailhead)
2. [Outbound] Takebashi Station → Nakabusa Onsen (overnight bus)
3. [Return] Nakabusa Onsen (Tsubakuro trailhead) → Hotaka Station
4. [Return] Nakabusa Onsen → Shinjuku Station (overnight bus)

1. [Outbound] Hotaka Station → Nakabusa Onsen (Tsubakuro trailhead)

From the front of JR Hotaka Station on the Oito Line, take the “Nakabusa Onsen regular bus” operated by Nan-an Taxi and get off at Nakabusa Onsen. The Tsubakuro trailhead is the bus terminus.

Ride time : 55 min
Fare : ¥1,500
Operating period : roughly late April to early November, on designated days

Each operating day falls into one of three patterns — A, B or C — with different numbers of services. An A day has six services including the early 5:15, a B day has five (the 5:15 is suspended), and a C day has no morning services so the first bus is at 11:10, only three services. On peak designated days (marked with ○ on the operating calendar) an extra 4:30 service is added to the A pattern. Always check which pattern applies on your day on Nan-an Taxi’s official operating calendar.

Bus timetableHotaka Station to Nakabusa Onsen

Source : Nan-an Taxi, Nakabusa Onsen regular bus (operating calendar)

2. [Outbound] Takebashi Station → Nakabusa Onsen (overnight bus)

Take the Mainichi Alpen-go “Tsubakuro / Jonen / Cho” bus from “Takebashi Station” on the Tokyo Metro Tozai Line and get off at the Tsubakuro trailhead, Nakabusa Onsen. Reservation only.

Takebashi Station (Tozai Line) gather 22:45, depart 23:00 (Mainichi Shimbun west-entrance lobby)
Tsubakuro trailhead, Nakabusa Onsen arrive around 5:30–6:00

Ride time: about 6–7 hours (overnight)
Fare: ¥8,800–13,800 (varies by season and seat; reservation required)

Details : Mainichi Alpen-go hiking bus, Tsubakuro / Jonen / Cho

3. [Return] Nakabusa Onsen (Tsubakuro trailhead) → Hotaka Station

From Nakabusa Onsen, take the “Hotaka Station regular bus” operated by Nan-an Taxi and get off at Hotaka Station.

Ride time : 55 min
Fare : ¥1,500
Operating period : roughly late April to early November, on designated days

The downhill services also vary by pattern. A and B days have five services, while on C days the two morning services (9:00 and 10:45) are suspended, leaving only three. The descent from Daitenso to Nakabusa Onsen takes about 5–6 hours, so allow margin for the return bus time.

Bus timetableNakabusa Onsen to Hotaka Station

Source : Nan-an Taxi, Nakabusa Onsen regular bus (operating calendar)

4. [Return] Nakabusa Onsen → Shinjuku Station (overnight bus)

From Nakabusa Onsen, take the Mainichi Alpen-go “Tsubakuro / Jonen / Cho” bus to the terminus, Shinjuku Station West Exit. Reservation only.

Nakabusa Onsen depart 12:45 or 13:45 (varies by date; check the link)
Shinjuku Station West Exit arrive around 18:00–19:00

Ride time: about 5–6 hours
Fare: ¥8,800–13,800 (varies by season and seat; reservation required)

Details : Mainichi Alpen-go hiking bus, Tsubakuro / Jonen / Cho

Route and safety notes

Route: Nakabusa Onsen → Kassen Ridge → Enzanso → Kaeru-iwa → Odori-no-Atama → Kiridoshi-iwa → Daitenso → Mt. Otensho (2,922 m). The total ascent time is about 7–8 hours, an advanced route with one night at Enzanso or Daitenso. From Enzanso to Mt. Otensho the path runs above the tree line with a grand view of Mt. Yari and the Hotaka peaks.

Hazards: Just before Daitenso, “Kiridoshi-iwa” is a rocky section with chains and an iron ladder, and the ground drops away near the Kisaku relief. In rain, strong wind or fog the risk of a fall or losing the way rises, so it is important to be willing to wait it out at a lodge.

Lodges, water and season: There is almost no water source on the ridge, so buy drinking water at the lodges. The best season is early July to early October; outside it, snow and ice make it unsuitable for general hiking. The lodges require reservations, so confirm in advance.
・Enzanso reservations 0263-32-1535
・Daitenso / Otensho Hütte reservations 0263-83-5810

Gear and emergencies: Carry rain gear, warm clothing, a headlamp, a map/GPS, and ample water and food. In an accident or emergency, call 110 (police) or 119 (fire/rescue).
・Azumino City Hall 0263-71-2000

Photo by Alpsdake / Wikimedia Commons, CC BY-SA 3.0