Tied for Japan's third-highest summit
Mt. Aino (Aino-dake) stands at 3,190 m (10,466 ft) on the border of Yamanashi and Shizuoka Prefectures, in the heart of Japan's Southern Alps. The name simply means "the in-between peak" — Aino sits between Mt. Kita (3,193 m) to the north and Mt. Nōtori (3,026 m) to the south, forming the central peak of the Shirane Sanzan ("three white peaks"). It is on the Hyakumeizan list.
After a 2014 GPS resurvey by the Geospatial Information Authority of Japan, Aino's official elevation was revised from 3,189 to 3,190 m, making it tied with Oku-Hotaka as Japan's third-highest mountain (after Fuji at 3,776 m and Kita at 3,193 m). Despite that statistical distinction, Aino's name recognition lags well behind both Kita and Oku-Hotaka. Hikers experience it less as a destination summit than as a peak you pass through on a traverse — and yet the Kita-Aino-Nōtori ridge is one of only two stretches in Japan that hold above 3,000 m for any meaningful distance.
There is no Aino-only route
Aino has no dedicated trailhead. The ridge connects to Kita to the north and to Nōtori to the south. To the west, the Sen-shio ridge eventually drops toward Sen-jō; to the east the slopes plunge into the wild Ōigawa headwaters. There is no way to climb only Aino — it has to be done as part of the Shirane Sanzan traverse.
The standard plan is the Hirogawara to Narada traverse, three days, two nights: climb to Kita-dake from Hirogawara, sleep at Kita-dake Sansō, tag Aino and Nōtori the next day, sleep at Nōtori Hut, and descend to Narada via Daimon-sawa on day three. This is the most efficient way to collect three Hyakumeizan summits (Kita, Aino, Nōtori) in a single trip. Strong, experienced parties run it in two days; the reverse direction (Narada → Hirogawara) is also common.
An experienced-only alternative is the Sen-shio ridge route via Ryōmata Hut, approaching Aino from the west by way of Mitsumine-dake. Three days minimum, with long quiet sections and minimal traffic — a second-visit option once a hiker knows the Shirane Sanzan from the standard direction.
Hirogawara and Narada: the two real trailheads
Access to Aino runs through the two Shirane Sanzan trailheads. Hirogawara is reached by Yamanashi-Kōtsū bus from JR Kōfu Station (about 2 hours via the Yashajin Pass), and is a private-car-restricted zone — drivers must switch to shared taxi or bus at Ashiyasu or Yashajin parking. Bus schedules thin out in shoulder season and the last buses leave Hirogawara early in the afternoon.
Narada is the terminus of the Hayakawa-chō municipal bus from JR Shimobe-Onsen Station (Minobu Line). Bus frequency is genuinely low, so the realistic plan is to stay overnight at Narada Onsen and catch an early morning bus through to Hirogawara to start the traverse. Even logistics-wise, Aino is not a casual Hyakumeizan.
A broad summit, and what walks on it
The summit itself is a wide, gentle dome of dwarf pine and scree — nothing like Kita-dake's pointed shoulder or Yari's spire. Without a striking landmark, the top looks unphotogenic in comparison to its neighbours, which is part of why Aino is called "the forgettable third-highest." But standing on it, the scale of the plateau itself is the point — a long, slowly curving roof, more like the high tundra of the Western US than a Japanese peak.
The Aino summit zone is a known habitat for the Japanese ptarmigan (rai-chō); foggy summer mornings sometimes produce sightings of mother birds with chicks in the dwarf pine. Alpine flora is rich: komakusa, takane-biranji, shinano-kinbai and hakusan-ichige bloom along the ridge in July and August. On the Shirane Sanzan traverse, much of the experience is exactly this — small flowers underfoot for hours, between the named summits.
Gear and weather for a 3,000-metre traverse
Aino requires a full Northern-Alps-grade traverse kit. The summit sits roughly 18–20 °C below the Kōfu basin, and even high summer dawns can drop to near freezing on the ridge. A fleece, light down, wind shell, full rain kit, gloves and a beanie are all baseline; ridge weather changes as quickly as anywhere in the country.
The headline hazard is afternoon thunderstorms on an entirely exposed ridge. At 3,000+ metres you are walking just under cloud base — there is nowhere to hide. The standard rule of thumb is to be back at Kita-dake Sansō or Nōtori Hut by 13:00, with a hard cutoff at 14:00. Snowfields in early July, particularly on the north faces between Kita and Aino, may still need light traction.
Two often-overlooked factors at this altitude: acclimatisation and UV. Hikers from sea level often push too hard on day one and feel altitude headache that night. Plan a deliberately slow pace on the climb to Kita-dake Sansō, drink water on a schedule (2 L+ per day at altitude), and wear sunglasses, sunscreen and lip balm. Day-hike kit and discipline produce visibly slower hikers by the morning of day three.
The view, and why Aino only makes sense as part of three
From Aino you see Kita-dake's sharp shoulder rising due north, with Sen-jō and Kai-Koma beyond it. Nōtori-dake sits south, with Shiomi and the Arakawa-Akaishi-Hijiri spine of the deep Southern Alps stretching on. Eastward stand Mt. Fuji and Yatsugatake, westward the Central and Northern Alps. The 360-degree view from a tie for Japan's third-highest summit is not a lesser version of Kita or Oku-Hotaka. At dawn, when Kita-dake's pyramid catches morgenrot, the best place to see it from is Aino.
The hiking season tracks the huts: mid-July through late September. Lightning frequency increases after Obon (mid-August). The mid-September autumn foliage paints the lower slopes red and gold with nanakamado and dakekanba. First snow falls on the summit ridge in early October, the huts close in mid-October, and from then on Aino is a winter mountaineering objective on a different scale.
Trying to judge Aino as a standalone peak misses the point. The three peaks of the Shirane Sanzan — Kita, Aino, Nōtori — form one geographic unit, and Aino is the centre of it. Walk the whole ridge and the question of why Japan's third-highest summit feels so understated answers itself; the answer is written into the terrain, the weather, and a hundred years of mountain history.
