Mt. Okuchausu

Mt. Okuchausu (Okuchausuyama, 2474 m) lies on the western side of the Akaishi Mountains (Southern Alps), on the border of Iida City and Oshika Village in Nagano Prefecture, and is one of Japan’s 300 Famous Mountains.
The long ridge from Shirabiso Pass over Mt. Otaka to Mt. Okuchausu runs through deep primeval forest of Veitch fir and Japanese hemlock, a quiet route weaving through fallen timber. The summit (Terebi-daira) opens up to a wide view of the main Southern Alps crest, including Mt. Hijiri and Mt. Akaishi. The elevation gain is only about 650 m, but with many ups and downs the round trip from Shirabiso Pass takes about 8 hours — a day route for fit hikers, with an overnight beforehand recommended.
The gateway is Shirabiso Highland. Take a bus from Iida Station to Toyamago, then a taxi up to Shirabiso Highland.

Mt. Okuchausu is a forepeak of the deep southern Southern Alps. The trail is well maintained from Shirabiso Pass to Mt. Otaka, but beyond Mt. Otaka fallen trees increase, and past Mt. Iwamoto it is hard to keep to the standard times. The season is June to October, while the road is open and the lodge operating; outside it, snow and road closures make the route unsuitable for general hikers. Plan on an overnight, carry a headlamp and start early.

*Information last checked: June 14, 2026

Getting to the trailhead

1. [Outbound] Iida Station → Toyamago (Kagura-no-yu) → Shirabiso Highland
2. [Return] Shirabiso Highland → Toyamago (Kagura-no-yu) → Iida Station

1. [Outbound] Iida Station → Toyamago (Kagura-no-yu) → Shirabiso Highland

From Iida Station on the JR Iida Line, take the Shinnan Kotsu “Toyamago Line” bus to the Michi-no-Eki Toyamago (Kagura-no-yu) (year-round). From Kagura-no-yu it is about 40 minutes by taxi to the Shirabiso Pass / Shirabiso Highland trailhead; public transport ends at Toyamago, and beyond that you need a taxi or private car. As the bus arrives in the afternoon, the realistic plan is to stay the night at Shirabiso Kogen Amanogawa and take a taxi up to Shirabiso Pass the next morning.
Taxi and lodging: confirm the Toyamago–Shirabiso Highland taxi or any shuttle in advance with the Toyamago tourism association or the lodge (Shirabiso Kogen Amanogawa, tel. 050-3583-2302; closed in winter).

Bus timetable: Iida Station → Kagura-no-yu (Michi-no-Eki Toyamago, Shinnan Kotsu Toyamago Line)

Reference: [Shinshu Toyamago Tourism Association] / [Shirabiso Kogen Amanogawa access]

2. [Return] Shirabiso Highland → Toyamago (Kagura-no-yu) → Iida Station

After descending, take a taxi from Shirabiso Highland / Shirabiso Pass down to the Michi-no-Eki Toyamago (Kagura-no-yu), then the Shinnan Kotsu Toyamago Line bus back to Iida Station. Book the taxi in advance. Buses from Kagura-no-yu are limited, so check the times against your descent.

Bus timetable: Kagura-no-yu (Michi-no-Eki Toyamago) → Iida Station (Shinnan Kotsu Toyamago Line)

Reference: [Shinshu Toyamago Tourism Association]

Climbing route and trail time

Route: round trip from Shirabiso Pass (day trip, overnight recommended)
Shirabiso Pass (1833 m) → Mae-Otakayama (2089 m) → Mt. Otaka (2212 m, about 2 hours) → Oku-Otakayama (2266 m) → Mt. Iwamoto (2269 m) → Mt. Okuchausu (2474 m, about 2 hours from Mt. Otaka). The round trip is about 15.7 km with around 1202 m of ascent and roughly 8 hours of walking (about 10 hours with breaks). The trail is well maintained from Shirabiso Pass to Mt. Otaka, but beyond Mt. Otaka fallen trees increase, and past Mt. Iwamoto the timber makes it hard to keep to the standard times. The elevation gain is only about 650 m, but the many ups and downs make it more tiring than expected. The summit, Terebi-daira (the site of a former relay reflector), is open, with a view of the main Southern Alps crest including Mt. Hijiri and Mt. Akaishi. Descend by the same route.

Because the route is long, stay overnight at Shirabiso Highland and start at first light. To avoid losing the way at dusk or in the fallen-timber zone, carry a headlamp, a map and compass (GPS).

Lodging

Shirabiso Kogen Amanogawa (Kamimura, Iida City; about 10 minutes’ walk south of Shirabiso Pass): the lodge at the Shirabiso Highland trailhead, a base for the night before or after. Tel. 050-3583-2302 (in season) / 0260-31-0036 (closed in winter). It is closed in winter (about December to March), and the road to Shirabiso Highland is also closed then.

There are no mountain huts or water sources on the trail. The Okuchausu route is a day trip with no staffed huts or water en route, so carry all the water and food you need. Use the toilet at Shirabiso Highland beforehand.

Lodging on the Toyamago side: there are also places to stay around Kagura-no-yu (Michi-no-Eki Toyamago), so you can stay there after the bus and take a taxi up to Shirabiso Highland the next morning.

Hazards, gear and best season

Difficulty: there are no chains or rock faces, but the long ridge from Shirabiso Pass to Mt. Okuchausu takes about 8 hours of walking and the fallen-timber zone slows the pace. It is a day route for fit hikers demanding stamina and time management, with an overnight assumed.

Fallen timber and route-finding: beyond Mt. Otaka, especially past Mt. Iwamoto, there is much fallen timber and the path is faint in places. Carry a map and compass (GPS) and check your position often so as not to lose the way in cloud or residual snow.

Access constraints: there is no public transport to Shirabiso Pass, only a taxi from Toyamago or a private car, and the road to Shirabiso Highland is closed in winter. Arrange the overnight and taxi and check road conditions in advance.

Water and toilets: there are no water sources, toilets or staffed huts on the trail. Carry plenty of water and food, and use the toilet at Shirabiso Highland.

Season and gear: the season is June to October, while the road is open and the lodge operating (the autumn colours are most comfortable). Carry rain gear, warm layers, a headlamp and plenty of water and food, file a climbing plan, and start early to descend before dark.

In an emergency: call 110 (police) or 119 (fire and rescue).
– Iida Police Station 0265-22-0110

Photo by Alpsdake / Wikimedia Commons, CC BY-SA 4.0