Mt. Okomori

Mt. Okomori (Okomoridake, 2767 m) stands on the border of Yamanashi and Shizuoka prefectures on the Shirane-nanrei ridge of the Southern Alps, and is one of Japan’s 100 Highest Mountains (ranked 73rd).
A gentle, creeping-pine-clad summit set between Mt. Shirakouchi and Mt. Hirokouchi, it lies on the Shirane-nanrei traverse running south from Mt. Notori, offering a quiet ridge walk with views of Mt. Shiomi and Mt. Fuji. The usual approach starts at Narada: climb the Sasayama Direct Ridge to Mt. Sasa (Kurokouchidake), then head north along the Shirane-nanrei over Mt. Shirakouchi, Mt. Okomori and Mt. Hirokouchi. There are no mountain huts on the ridge itself, so tent camping is the norm and this is a long route for fit, experienced hikers.
The gateway is Narada. A community bus run by Hayakawa Town reaches Narada from stations on the Minobu Line, so it can be approached by public transport.

The climb starts at Narada: the Sasayama Direct Ridge (about 13 km round trip, roughly 1944 m of ascent) leads up to Mt. Sasa, from where you follow the Shirane-nanrei ridge over Mt. Shirakouchi (2813 m) → Mt. Okomori (2767 m) → Mt. Hirokouchi (2895 m). It takes about 6 hours 30 minutes of steep climbing from Narada to the South Peak of Mt. Sasa, then about 2 hours 30 minutes more along the ridge from the North Peak of Mt. Sasa to Mt. Okomori; the classic loop continues north over Mt. Hirokouchi and the Daimonzawa descent point down into the Daimonzawa valley, taking two nights and three days (or one night for the very fit). There are no huts on the ridge, so hikers tent-camp on the flats near Mt. Shirakouchi and Mt. Okomori; the Daimonzawa-goya hut lies lower down on the descent.
The only water source is partway up the Sasayama Direct Ridge — there is none on the ridge crest — so carry plenty of water. The season runs from late June to October; outside it, beware of residual snow and ice. A topographic map and compass (GPS) are essential.

*Information last checked: June 14, 2026

Getting to the trailhead

1. [Outbound & Return] Shimobe-onsen / Minobu Station → Narada (Sasayama Direct Ridge trailhead)

1. [Outbound & Return] Shimobe-onsen / Minobu Station → Narada (Sasayama Direct Ridge trailhead)

To reach the gateway of Narada, take the Hayakawa Town community bus from Shimobe-onsen Station or Minobu Station on the JR Minobu Line to Narada Onsen (about 1 hour 30 minutes from Minobu Station, fare 1000 yen, plus 200 yen for a large backpack; runs almost year-round). In summer you can also come in from Kofu Station on the Yamanashi Kotsu South Alps climbing bus (change at Hirogawara for the Hirogawara–Narada leg; seasonal service, typically late June to early November). It is safest to stay overnight at Narada Onsen and set off early; check the bus times and operating periods in advance via the official Hayakawa Town and Yamanashi Kotsu information.
– Hayakawa Town community bus (Town Hall) 0556-45-2511 / Yamanashi Kotsu 055-223-0821

Reference: [Hayakawa Town official site]

Climbing routes and trail times

Route 1: Shirane-nanrei loop (classic, 2 nights 3 days / 1 night for the fit)
Narada → Sasayama Direct Ridge trailhead → water-source junction → Mt. Sasa (Kurokouchidake), South and North Peaks (about 6 hours 30 minutes from Narada) → Mt. Shirakouchi (2813 m, about 1 hour 30 minutes) → Mt. Okomori (2767 m, about 1 hour) → Mt. Hirokouchi (2895 m, about 1 hour 45 minutes) → Daimonzawa descent point (about 20 minutes) → Daimonzawa-goya hut (about 2 hours) → Narada (about 3 hours). The Sasayama Direct Ridge is an advanced route with around 2000 m of continuous steep ascent; most hikers tent-camp near Mt. Sasa or Mt. Shirakouchi on the first day, then cross Mt. Okomori and Mt. Hirokouchi and descend into the Daimonzawa on the second. The ridge over Mt. Shirakouchi, Mt. Okomori and Mt. Hirokouchi is open creeping-pine terrain with fine views, but the path is faint in places with collapsed sections, so route-finding is required.

Route 2: out-and-back from Mt. Sasa (Okomori return trip)
Climb the Sasayama Direct Ridge to the North Peak of Mt. Sasa, then cross Mt. Shirakouchi and make a return trip to Mt. Okomori — about 2 hours 30 minutes one way from the North Peak of Mt. Sasa. This avoids the Daimonzawa descent, so the route is simpler, but it combines the Sasayama round trip with a ridge out-and-back and makes for a long day. Either way water is scarce, so secure enough before heading up onto the ridge.

Huts and tent camping

There are no mountain huts on the Shirane-nanrei ridge. The stretch over Mt. Sasa, Mt. Shirakouchi, Mt. Okomori and Mt. Hirokouchi is an unmanned ridge, and tent camping on the flats near Mt. Shirakouchi or Mt. Okomori is the norm (these are not designated sites, so keep camping minimal and protect the environment). The only water source is partway up the Sasayama Direct Ridge, none on the crest, so carry up all the water you need.

Daimonzawa-goya (on the Daimonzawa route, about 1750 m): a hut on the descent from Mt. Hirokouchi into the Daimonzawa, open July 1 to October 14, 2026. Reservations by phone (tel. 090-7635-4244, 9:30–17:00); check-in 14:00–16:00. Staying here on the way down lets you split the long Daimonzawa descent over two days.

Narada Onsen: there is lodging at the Narada trailhead, useful as a base for the night before or after. Check reservations and opening periods on each operator’s website or by phone.

Hazards, gear and best season

Difficulty: Mt. Okomori sits deep on the lightly maintained Shirane-nanrei, and the combination of the steep Sasayama Direct Ridge, a long ridge traverse and tent camping makes this an advanced route demanding both stamina and experience. Even for strong hikers a day trip means a 15-hour-plus effort.

Sasayama Direct Ridge: about 2000 m of continuous steep ascent from Narada to Mt. Sasa. Start early and manage your pace and water carefully.

Route-finding on the ridge: the crest over Mt. Shirakouchi, Mt. Okomori and Mt. Hirokouchi is creeping-pine terrain with faint sections and collapsed ground, and is easy to lose in cloud. Carry a map and compass (GPS), and do not push on in poor visibility.

Water: the only source is partway up the Sasayama Direct Ridge; there is none on the crest. Carry up all the water you need for camping and the traverse.

Few escape options: there are few huts or easy descents on the ridge, so retreating in bad weather is hard. Decide to turn back before the weather breaks.

Season and gear: the season runs late June to October; outside it, beware of residual snow and ice. Carry rain gear, warm layers, a headlamp, tent-camping equipment and plenty of water and food, and always file a climbing plan.

In an emergency: call 110 (police) or 119 (fire and rescue).
– Hayakawa Town Hall 0556-45-2511 / Nanbu Police Station 0556-64-2611

Photo by Alpsdake / Wikimedia Commons, Public domain