The mountain that named the Southern Alps
Mount Akaishi rises on the main ridge of the Akaishi Mountains, better known as the Southern Alps, where the ridge coming from the north turns west-south-west towards Ōsawa-dake. Only Kita-dake, Aino-dake and Warusawa-dake (the highest summit of Mount Arakawa) are higher in the range. Its height has long been given as 3,120 m; after a GNSS re-survey in 2014 the Geospatial Information Authority of Japan revised it to 3,120.5 m. About 700 m north of the summit stands the subsidiary peak of Ko-Akaishi-dake (3,081 m), and the eastern ridge that carries the main route leaves the crest between the two.
The summit holds a first-order triangulation point named "Akaishi-dake", the highest such point in Japan. On the eastern slopes below the crest lie several cirques, the southernmost traces of Ice Age glaciers in the country; on the south-west slope there is a boulder field that is a fossil rock glacier, and near the top are linear depressions. To the west, between Akaishi and Ōsawa-dake, the flat ridge called Hyakken-daira is a remnant of an uplifted peneplain. On a clear morning Mount Fuji is in view 53 km to the east; the neighbours Mount Arakawa (4.9 km to the north) and Mount Hijiri (3,013 m, 4.6 km to the south-south-west) are also among the 100 Famous Mountains.
Where it is and how to get there
The summit lies on the border of Shizuoka City (Aoi ward) and Ōshika village in Nagano Prefecture, inside Minami Alps National Park (since 1964) and the Minami Alps UNESCO Biosphere Reserve. The Shizuoka side, around the headwaters of the Ōi River, is the private Ikawa forest of the Tokushu Tokai Paper company; its subsidiary Tokushu Tokai Forest runs most of the huts in the southern part of the range.
From Shizuoka (the normal approach). Shinkansen to Shizuoka station, then about 63 km of mountain roads to the Hatanagi Dai-ichi Dam. In summer the Shizutetsu Justline bus runs once a day to the Hatanagi summer car park, about 3 h 20 min; it is reservation-only and the dates change from year to year. Drivers leave the car at the free summer car park about 2 km below the dam (around 300 spaces, temporary toilets). Beyond the Numadaira gate the Higashimata forest road (27.3 km) is closed to private cars: Shizuoka City does not issue permits for hiking or leisure.
The only motor transport to the trailhead is the Tokushu Tokai Forest shuttle bus from the Hatanagi summer car park to Sawarajima Lodge (1,120 m), about 1 h 10 min. In 2026 it ran from 11 July to 12 October, leaving Hatanagi at 7:30 and 15:00 and Sawarajima at 6:10, 10:30 and 13:00. The return ride is free for anyone staying at least one night (room only or more) at Sawarajima Lodge, Senmai hut, Akaishi hut, Arakawa hut, Hyakkenbora hut or the Akaishi summit shelter; tent-only trips are not eligible. Seats must be booked together with the hut, except in late September and early October (24 September to 9 October in 2026), when you simply queue. Passengers wear a helmet, which the company lends. Outside the main period the transfer is arranged individually when booking the lodge, because of works on the forest road.
From Nagano. The nearest railway station on the west side is Iida on the JR Iida Line, about 31 km away. Prefectural road 253 leads from Ōshika village up the Koshibu River, where the Koshibu route starts; another approach comes from the Shirabiso Pass via the Ōsawa hut to Ōsawa-dake. Both are long, little-used routes (see below).
Huts, booking and costs
Prices below are those published by Tokushu Tokai Forest and its booking centre for the 2026 season:
- Sawarajima Lodge (1,120 m, about 200 places, baths, campsite): open from 26 April into November; in July–September room only costs 10,000–12,000 yen per person depending on how many share the room. Dinner 2,500 yen, breakfast or breakfast box 1,500 yen.
- Akaishi hut (Akaishi-goya, 2,535 m, about 100 places, 15 tent pitches): open 11 July to 11 October; 11,000 yen room only, about 15,000 yen with dinner and breakfast. From 11 to 15 July and from 23 September only room-only stays are offered.
- Akaishi summit shelter (Akaishidake hinan-goya, just below the summit on the south side, about 40 places): staffed 11 July to 22 September; 11,000 yen, no meals, so bring your own food.
- Arakawa hut (2,652 m, between Arakawa-maedake and Ko-Akaishi-dake): same season and prices as Akaishi hut.
- Hyakkenbora hut (Hyakkenbora yama-no-ie, on the traverse to Mount Hijiri): 11,000 yen room only; in 2026 it closed on 31 August for renovation, while its campsite stayed open.
Tent pitches cost about 2,000 yen. From 11 July to 22 September all these places must be booked in advance, online or by phone, through the Tokushu Tokai Forest booking centre, and the stay is paid in advance; outside that window the lodge takes bookings by phone. Arriving without a booking where one is required costs an extra 1,000 yen and does not guarantee a bed. Out of season most huts keep part of the building open as an emergency shelter. There is no fee for entering the national park.
Routes
Ōkura ridge (east ridge) from Sawarajima, the normal route. From Sawarajima the trail follows an old logging track and then climbs the very steep, viewless forest of the Ōkura ridge, with ladders and chains in places, to Akaishi hut (2,535 m), about 5 h 20 min. About 45 minutes beyond, Fujimi-daira (2,700 m) opens the view to Mount Fuji and Mount Hijiri. Above the tree line the path crosses rocky, exposed ground and the narrow "Camel's Back" to the junction below the crest (about 3,000 m), 2 h 10 min from Fujimi-daira, and reaches the summit in another 30 min. The ascent totals about 8 h 45 min and 2,000 m; the descent to Sawarajima takes about 6 h 20 min. Most people spend the night before at Sawarajima Lodge, climb to Akaishi hut on day one, go to the summit at dawn and catch an afternoon bus down.
Arakawa loop. The popular three- or four-day circuit climbs from Sawarajima past Shimizu-daira and Komadori pond to Senmai hut (2,565 m, about 6 h 35 min), crosses Senmai-dake (2,880 m), Warusawa-dake (3,141 m), Naka-dake (3,083 m) and Mae-dake (3,068 m) to Arakawa hut, then follows the main ridge over Daishōji-daira and Ko-Akaishi-dake to Akaishi (about 2 h 50 min from Arakawa hut) and descends the Ōkura ridge. Walking time is about 21 hours over roughly 27 km. The ridge beyond Senmai is rocky and needs care on snow patches early in the season.
Traverses. Akaishi lies on the long north–south traverse of the Southern Alps: from the north via Shiomi-dake, Sanpuku Pass and Mount Arakawa, from the south via Hijiri-daira, Mount Hijiri, Usagi-dake and Hyakken-daira, with Hyakkenbora hut as the usual night stop between Akaishi and Hijiri.
Koshibu River route (Nagano). The route on which Walter Weston made his ascent in 1892 follows the Koshibu River with many fords to the unstaffed Hirogawara hut (about 30 places), then climbs past Funakubo to the main ridge at Daishōji-daira. After rain the river can become impassable, and the access road has been damaged by landslides, so this route is only for experienced parties who check its current state with Ōshika village first.
Winter and spring
The Higashimata forest road is closed to all traffic, walkers and cyclists included, from 26 December to 25 April (2026–2027 season), and the huts on the mountain close in mid-October. In practice Akaishi in winter is an expedition for experienced mountaineers. Snow lies on the upper Ōkura ridge until mid-May, so climbers who come when Sawarajima Lodge opens in late April need crampons, an ice axe and the skills to use them; from November snow and ice return, and winter gear is again required. On the upper ridge, look for the paint marks: a signposted "winter route" branches off and is not the summer path.
When to go and weather
The hiking season is mid-July to early October, when the huts and the shuttle bus operate. July brings alpine flowers but often ends the rainy season with heavy downpours; late July and August are the busiest weeks; September and early October are quieter, with autumn colours, but meals at the huts are no longer served after 22 September. Typhoons in late summer and autumn are the main problem: when heavy-rain warnings are issued for northern Shizuoka City the forest road is closed and the shuttle stops. On the open ridge expect strong wind, fog and afternoon thunderstorms, and cold nights even in midsummer.
Water
There is no reliable water on the Ōkura ridge between Sawarajima and Akaishi hut, so carry at least 1.5–2 litres for the 5–6 hour climb. Akaishi hut has water; above it, a spring at the head of the Kita-sawa stream below the crest is the last place to fill bottles before the summit. The summit shelter has no water source. On the Arakawa loop there is water at Shimizu-daira and below Mae-dake on the way to Arakawa hut, but the latter can dry up. Ask at each hut how much water they can give or sell, and treat stream water.
Mobile coverage and internet
Coverage is patchy. Sawarajima and the deep valleys of the Ōi headwaters are among the most isolated places in Honshu, and in the forest of the Ōkura ridge there is often no signal; on the open crest near the summit and on the Arakawa ridge a phone may connect. Do not count on Wi-Fi at the huts. Carry a fully charged phone and a power bank, download offline maps, and leave your plan with someone at home. In an emergency call 110 (police, who handle mountain rescue) or 119 (fire and ambulance).
Akaishi-dake is one of the Southern Alps peaks on Nagano Prefecture's designated trails, where a climbing notification (tozan-todoke) is mandatory under the prefectural mountain safety ordinance; file it online through the Nagano e-application service or the Compass or YAMAP apps, by fax or at a trailhead box, and carry a copy.
Dangers and safety
The main danger is the length of the day: 2,000 m of ascent on steep, rough ground followed by exposed rock above 2,700 m. Slips on wet rock and loose stones on the ridge, fog on the broad summit area, lightning and hypothermia in summer storms are the usual causes of trouble. Asian black bears and sika deer live in the forests.
Access itself is fragile. On 25 July 2025 a landslide blocked the forest road below Sawarajima and at least 117 hikers, hut guests and workers were cut off; most walked out on a detour opened by Shizuoka City the next day. On 21 March 2026 another collapse isolated 79 people at Shirakaba-sō, Sawarajima and Nikenkoya. Build a spare day into your plan, and check the road and bus status before you leave.
Nature
The upper slopes from Ko-Akaishi-dake to the summit are covered with Japanese stone pine and wide alpine meadows, a habitat of the rock ptarmigan. The area is home to Akaishi-rindō, a gentian named after the range and listed as endangered on the Ministry of the Environment's Red List. Below the tree line grow old-growth forests of Erman's birch, Veitch's fir, spruce and hemlock; Japanese serow, Asian black bears and sika deer are common, and char and amago trout live in the gorges of the Akaishi-sawa.
History and name
The name means "red stone". It comes from the red radiolarian chert in the bedrock of the Akaishi-sawa, the Ōi tributary that rises on the southern slope; another explanation is that the whole mountain looks reddish beside its neighbours. The Sunga-ki chronicle of 1820 already wrote it as 赤石嶽, and the name of the mountain was later extended to the entire range.
- 1879: Nashiba Haruki and Terasawa Masaaki of the Home Ministry's land survey made the first recorded ascent while surveying.
- 1886: Horimoto Jōkichi opened a path to the summit; around 1901–1902 many groups of religious pilgrims climbed it. A first-order triangulation point was set on the top at the end of the century.
- 19 August 1892: the English missionary Walter Weston became the first foreigner on the summit, climbing from the Koshibu River. Earlier in the Meiji era the geologist Edmund Naumann and the botanist Kōno Reizō had also reached the top.
- 1906: Kojima Usui described the mountain in the first issue of the Japanese Alpine Club's journal Sangaku; in July 1909 his party traversed from Nishiyama Onsen over Warusawa-dake to Akaishi and down the Koshibu River.
- Summer 1926: Ōkura Kihachirō, head of the Ōkura business group and founder of one of the companies that became Tokushu Tokai Paper, wanted "to climb the highest point of my own land". Aged 88, he was carried up in a palanquin with about 200 porters; the trip cost 40,000 yen, more than 100 million yen in today's money.
- 1957: the mountaineering events of the 12th National Sports Festival were held in the Southern Alps, and climber numbers grew. In 1964 the area became part of Minami Alps National Park.
Interesting facts
- Its first-order triangulation point is the highest in Japan; the lowest mountain with a first-order point, Sotetsu-yama in Sakai (Osaka), is under 7 m high.
- The asteroid (53157) Akaishidake, discovered on 5 February 1999, is named after the mountain.
- Because the Shizuoka side is company land, the shuttle bus is formally the "pick-up bus" of the company's lodges, which is why only hut guests may ride it.
FAQ
How high is Mount Akaishi? 3,120 m (3,120.5 m after the 2014 re-survey). It is the seventh-highest mountain in Japan and the fourth-highest in the Southern Alps.
How long does it take to climb? Via the Ōkura ridge, about 8 h 45 min up and 6 h 20 min down, with about 2,000 m of ascent. Most people take two days with a night at Akaishi hut, plus a night at Sawarajima Lodge before. The Arakawa loop takes three to four days.
How difficult is it? It is a long, steep hike rather than a climb, but with ladders, chains and exposed rock near the top. Good fitness and mountain experience are needed; it is not a beginner's peak.
How do I get to the trailhead? Bus or car from Shizuoka to the Hatanagi summer car park, then the Tokushu Tokai Forest shuttle to Sawarajima, free if you book at least one night in its huts (11 July to 12 October in 2026). Private cars are not allowed on the forest road.
How much do the huts cost? In 2026, 11,000 yen room only at Akaishi hut and the summit shelter, about 15,000 yen with two meals at Akaishi hut, and about 2,000 yen for a tent pitch. Booking is required from 11 July to 22 September.
Is there water on the way? Not between Sawarajima and Akaishi hut; carry 1.5–2 litres. Akaishi hut has water, and there is a spring at the head of the Kita-sawa below the crest. The summit shelter has none.
Is there mobile coverage? Unreliable: often none in the forest and valleys, sometimes a signal on the open ridge. Emergency numbers are 110 and 119.
When is the best time to climb? Mid-July to early October, when the huts and shuttle run. Late July and August are busiest; September is quieter. Outside that season it is a winter mountaineering objective with no road access in deep winter.
Do I need to file a climbing plan? Yes: Akaishi-dake is on Nagano Prefecture's list of designated trails, where a climbing notification is mandatory. It can be filed online or through the Compass or YAMAP apps.