Mt. Io

Mt. Io (硫黄岳) is a 2,760m peak located near the center of the Yatsugatake Range. The large-scale cliff terrain spreading on the north side of the summit (commonly introduced as the “explosion crater”) is spectacular, and the peak serves as a key point on the ridge that continues south to Mt. Yoko and Mt. Aka, and north to Mt. Tengu. It is popular for Yatsugatake central-northern traverses and as an alpine debut for beginner-to-intermediate hikers.

Trails include: from Minotoguchi via Akadake Kosen up to near the summit; from Sakuradaira / Natsuzawa Kosen via Sekigan-no-Atama to the summit; and the ridge traverse from the Mt. Aka direction passing near the summit toward Mt. Tengu.

This page introduces access by bus to Minotoguchi, the Inako trailhead, and Inakoyu.

＊Timetable last checked: June 6, 2026

How to access the trailheads

1. [Outbound] Chino Station → Minotoguchi
2. [Outbound] Takebashi Station → Minotoguchi (highway bus)
3. [Outbound] Koumi Station → Inako Trailhead → Inakoyu
4. [Return] Minotoguchi → Chino Station
5. [Return] Minotoguchi → Shinjuku Station (highway bus)
6. [Return] Inakoyu → Inako Trailhead → Koumi Station

1. [Outbound] Chino Station → Minotoguchi

From JR Chuo Main Line Chino Station West Exit Platform 4, take the Alpico Kotsu Minotoguchi Line to the terminus Minotoguchi.
Fare: ¥1,900 (adult one-way, revised August 2025, continued for 2026 season)
Travel time: about 38 minutes
Operating days: Sat/Sun/holidays + daily from 8/1–8/30 (no weekday service)
Operating period: May 2 – October 25, 2026

Bus TimetableMinotoguchi Line (toward Minotoguchi) Timetable

Reference: [Alpico Kotsu Minotoguchi Line]

2. [Outbound] Takebashi Station → Minotoguchi

※ Mainichi Alpen-go 2026 season info: Departures from the Kanto area (Takebashi, Shinjuku) will go on sale in sequence as the 2026 operating information is confirmed (as of 2026-05-11). Please check the latest operating calendar on the official site. The following is based on 2025 actual operations.

From Tokyo’s Takebashi and Shinjuku, the Mainichi Alpen-go by Maitabi (Mainichi Shimbun Travel) runs direct to Minotoguchi (in front of Yatsugatake Sanso) (seasonal operation, reservation required).
Travel time: about 6 hours Fare: about ¥8,000–10,000 (varies by plan)

Main schedule (reference): Takebashi dep. 22:30 / Shinjuku dep. 23:00 → Minotoguchi arr. around 4:30–5:10
Some plans include late-night arrival with rest, and the routing varies by date. Please check the official course pages for the latest information.

Reference: [Alpen-go (morning arrival, outbound)] / [Yatsugatake departure, return].

3. [Outbound] Koumi Station → Inako Trailhead → Inakoyu

※ Koumi Town Bus Matsubarako Line 2026 season info: Due to bridge repair work, service toward Inakoyu was suspended from 2025/11/3, but resumed from April 25, 2026. Koumi Station ↔ Inakoyu adult fare ¥800. Please check the latest timetable on the Koumi Town official site.

From JR Koumi Line Koumi Station, take the Koumi Town Bus “Matsubarako Line” and get off at Inako Trailhead Entrance or Inakoyu.
Travel time: about 45 minutes Fare: ¥800 (to Inakoyu)
Operating period: April 25 – mid-December, 2026. In winter, many runs do not go all the way to Inakoyu — please check carefully.

Bus TimetableBus Timetable toward Inako Trailhead / Inakoyu

Reference: [Koumi Town Route Bus]
[Timetable revised April 1, 2025]

4. [Return] Minotoguchi → Chino Station

From Minotoguchi, take the Minotoguchi Line toward Chino Station.
Fare: ¥1,900 (adult one-way, revised August 2025, continued for 2026 season)
Travel time: about 38 minutes
Operating days: Sat/Sun/holidays + daily from 8/1–8/30 (no weekday service)
Operating period: May 2 – October 25, 2026

Bus TimetableFrom Minotoguchi bus stop to Chino Station

Reference: [Alpico Kotsu Minotoguchi Line]

5. [Return] Minotoguchi → Shinjuku Station

The Mainichi Alpen-go by Maitabi (Mainichi Shimbun Travel) runs direct to Shinjuku (seasonal operation, reservation required).
Travel time: about 3 hours Fare: about ¥5,500
Main schedule:
15:40 Minotoguchi dep. 15:40 → 18:45 Shinjuku Station → 19:15 Tokyo Station (Mainichi Alpen-go Yatsugatake direction / Mugikusa, Minotoguchi dep. (return) S102B02)
15:40 Minotoguchi dep. 15:40 → 18:45 Shinjuku Station → 19:15 Tokyo Station (Alpen-go Yatsugatake (return) W-seat / Minotoguchi dep. S102B01WS)
15:45 Minotoguchi dep. 15:40 → 18:45 Shinjuku Station → 19:15 Tokyo Station (Alpen-go Yatsugatake (return) W-seat / Minotoguchi dep. S102B01WS)

6. [Return] Inakoyu → Inako Trailhead → Koumi Station

From the Inakoyu or Inako Trailhead Entrance bus stop, take the Koumi Town Bus “Matsubarako Line” and get off at JR Koumi Station.
Travel time: about 45 minutes Fare: ¥800 (from Inakoyu)

Operating period: April 25 – mid-December, 2026. In winter, many runs do not go all the way to Inakoyu — please check carefully.

Bus TimetableBus Timetable from Inakoyu / Inako Trailhead

Reference: [Koumi Town Route Bus]
[Timetable revised April 1, 2025]