Mt. Jii

Mt. Jii (Jiidake, 2825 m) rises east of the Kumonodaira plateau in the deepest part of the Northern Alps, and is one of Japan’s 100 Highest Mountains.
It is the volcano that created the Kumonodaira lava plateau; its broad, flat summit is covered in quartz-andesite scree and cairns, and gives a 360-degree view of Mt. Suisho, Mt. Washiba, Mt. Yakushi, Mt. Kurobegoro and Kumonodaira — a fine viewpoint deep in the Northern Alps. It is the centrepiece of Kumonodaira, “Japan’s last wilderness,” only about 1 hour 20 minutes round trip from the Kumonodaira Sanso lodge, and is also climbed on the Mt. Suisho–Mt. Washiba circuit. The shortest approach is two nights and three days from Oritate via Tarodaira and Kumonodaira.
The gateway is Oritate. The summer mountain bus (Arimine Line) from Arimineguchi Station on the Toyama Chiho Railway reaches Oritate, so it can be approached by public transport.

Mt. Jii sits at the heart of Kumonodaira, ringed by Mt. Yakushi, Mt. Suisho and Mt. Washiba, and can also be reached on long traverses from Kamikochi or Shinhotaka Onsen. This article focuses on the shortest route from the Toyama side (starting at Oritate). The summit area is broad and gentle, so it is easy to lose your bearings in cloud — follow the cairns carefully. The season is mid-July to late September, while the summer bus runs and the huts are open.

*Information last checked: June 14, 2026

Getting to the trailhead

1. [Outbound] Toyama Station → Arimineguchi Station → Oritate (summer mountain bus)
2. [Return] Oritate → Arimineguchi Station → Toyama Station

1. [Outbound] Toyama Station → Arimineguchi Station → Oritate (summer mountain bus)

At JR Toyama Station transfer to the Toyama Chiho Railway, get off at Arimineguchi Station, and from in front of the station take the Toyama Chitetsu “summer mountain bus (Arimine Line)” to the terminus at Oritate. There is also a direct bus from in front of Toyama Station. Oritate is the shortest trailhead for Mt. Yakushi, the Kurobe headwaters and Kumonodaira. The summer bus usually runs mid-July to late September and is fully reservation-based; outside the season (October–June) there is no public transport to Oritate and entry is effectively impossible.
Time: Arimineguchi Station → Oritate about 60 minutes / in front of Toyama Station → Oritate about 2 hours 20 minutes. Fare: Arimineguchi Station → Oritate about 1800 yen / Toyama Station → Oritate about 3300 yen (round-trip tickets available). From Oritate to the Kumonodaira Sanso lodge is about 10 hours via Tarodaira and Yakushizawa (standard two nights three days).

Reference: [Toyama Chiho Railway summer mountain bus (Arimine Line)]

2. [Return] Oritate → Arimineguchi Station → Toyama Station

From the Oritate bus stop take the summer bus back to Arimineguchi Station or in front of Toyama Station. There are direct buses, and also services with a transfer at the Arimine Memorial Hall. Time: Oritate → Arimineguchi Station about 50 minutes / Oritate → Toyama Station about 2 hours; fares are the same as outbound. This too is fully reservation-based, so book from one month before to match your descent day. For a hot spring afterwards, get off one stop earlier at Kamegai Onsen to visit Shirakaba Heights.

Reference: [Toyama Chiho Railway summer mountain bus (Arimine Line)]

Climbing routes and trail times

Route 1: Oritate–Kumonodaira route (standard, two nights three days)
Day 1: Oritate → survey point → Tarodaira-goya lodge (about 5 hours, overnight). Day 2: Tarodaira → Yakushizawa-goya → Kumonodaira Sanso lodge (about 6 hours, overnight, with an afternoon walk around Kumonodaira). Day 3: Kumonodaira Sanso → Mt. Jii (2825 m, about 1 hour 20 minutes up, round trip) → Yakushizawa → Tarodaira → Oritate. Mt. Jii is the most easily climbed peak from the Kumonodaira Sanso lodge, and its broad summit gives a wide view of Mt. Suisho, Mt. Washiba, Mt. Yakushi and Mt. Kurobegoro.

Route 2: Mt. Suisho–Mt. Washiba circuit (three nights four days)
Oritate → Tarodaira → Kumonodaira → Mt. Jii → Mt. Warimo → Mt. Suisho → Mt. Washiba → Mitsumata Sanso → Kurobe headwaters → Tarodaira → Oritate. Mt. Jii is also a crossroads from the Kurobe headwaters and Iwakoke-norikoshi toward Mitsumata and Mt. Suisho, and a waypoint on long traverses from Shinhotaka Onsen over Mt. Sugoroku and Mt. Washiba.

Mountain huts and lodging

Kumonodaira Sanso (2560 m): the base for climbing Mt. Jii, capacity about 100 (tel. 080-1951-3030). The Kumonodaira campsite (toward Mt. Jii) is also available. Tarodaira-goya (2330 m) and Yakushizawa-goya (1900 m) are used for an overnight or staging on the way up from Oritate. All are open in summer from early July to early October and are fully reservation-based.

Huts on the traverse: for the Mt. Suisho–Mt. Washiba circuit, use Suisho-goya, Mitsumata Sanso, Sugoroku-goya and others. Check reservations and opening periods on each official website or by phone.

Water: water can be taken at the Oritate trailhead, Yakushizawa-goya, Tarodaira-goya and Kumonodaira Sanso. Carry plenty on the traverse.

Hazards, gear and best season

Difficulty: the climb of Mt. Jii itself is a gentle path with few hazards, but Kumonodaira is the “wilderness” deep in the Northern Alps, and it takes a standard two nights and three days from the Oritate trailhead to Kumonodaira. It assumes the stamina and schedule for a long approach and is not for beginners.

Route-finding on the broad summit: the summit of Mt. Jii is broad and gentle, and it is easy to lose your bearings in cloud. Follow the scattered cairns and always carry a map and compass (GPS).

Long approach: Oritate → Tarodaira → Yakushizawa → Kumonodaira involves large cumulative gain and distance, and the steep climb from Yakushizawa up to Kumonodaira is demanding. Escape options are few if the weather turns, so allow a generous schedule.

Access constraints: the summer bus runs mid-July to late September and is fully reservation-based; outside this, there is no public transport to Oritate and entry is difficult. Plan around the bus and hut operating periods.

Season and gear: the season is mid-July to late September, while the summer bus runs and the huts are open. Carry rain gear, warm layers, a headlamp and plenty of water and food, and always file a climbing plan. If camping, use the Kumonodaira campsite.

In an emergency: call 110 (police) or 119 (fire and rescue).
– Toyama Prefectural Police mountain rescue unit 076-441-2211

Photo by 住友快左衛門 / Wikimedia Commons, Public domain