Starting from Sakuradaira, the route passes Natsuzawa Kosen and Oren-goya up to Akaiwa-no-atama. Beyond the treeline a grand panorama of the main Yatsugatake ridge opens up — a celebrated peak of crater walls.
Source: GSI tiles (Geospatial Information Authority of Japan) ／ The route is the editor's measured YAMAP activity track (GPX).Scroll-zoom is enabled after you click the map.
Location & access
Coordinates are the trailhead and summit points from the editor's own GPS track.
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Editor's note
Iwodake (Mt. Iou) is a 2,760 m peak in the southern part of the Yatsugatake range. From its broad, gentle summit you can take in the main peaks of Akadake, Yokodake and Amidadake, while on the north side of the summit a huge explosion crater about 1 km in diameter and about 550 m deep gapes open. From the perspective of an editor who lives in Hokuto City and calls Yatsugatake home, and who actually made the round trip of the Akaiwa-no-atama route in deep winter, here are the points to help you decide.
Starting from Sakuradaira, you climb through the forest via Natsuzawa Kosen and Oren-goya up to Akaiwa-no-atama at the treeline. Here the view opens all at once, and the snow-clad main Yatsugatake ridge spreads out before you. From there to the summit it is a gentle climb over rock and snow. It is relatively easy among the main Yatsugatake ridge, but in deep winter the whole mountain is snow-covered, and crampons, an ice axe and protection against strong wind are indispensable.
The editor’s measured time, including breaks, was about 5 hours 5 minutes (departed 08:47, summited 11:50, descended 13:52). When the sky is clear, you can fully savour the power of the snow ridges and crater walls beneath the deep blue known as "Yatsugatake blue."
On this deep-winter trip (February 18, 2026), the editor mentions that the forest road to the Sakuradaira car park was also quite snow-covered ([video 1:36](https://www.youtube.com/watch?v=X4z9EnI3Jqc&t=96s)). Early in the route, the editor noticed a smell from the river and wondered aloud whether there might be a hot spring nearby ([video 19:03](https://www.youtube.com/watch?v=X4z9EnI3Jqc&t=1143s)). In this video, the editor also touches on a past experience of turning back just short of the summit due to a whiteout ([video 1:21](https://www.youtube.com/watch?v=X4z9EnI3Jqc&t=81s)).
In the snow-free season this is a mountain well suited even to a Yatsugatake beginner, but in deep winter it is for the experienced. Above the treeline the wind is strong, so on days of poor visibility rely on the cairns and proceed carefully. If the weather looks like turning, make sure to turn back early.
Routes
From Sakuradaira the route passes Natsuzawa Kosen and Oren-goya, climbing through forest to Akaiwa-no-atama. Once you cross the treeline the view opens all at once, and a gentle climb over rock and snow leads to the summit. It is relatively easy among the main Yatsugatake ridge, but in deep winter the whole mountain is snow-covered and crampons and an ice axe are essential. The editor also made this round trip in deep winter.
The classic approach, climbing from Minoto via Akadake Kosen up to Akaiwa-no-atama. It is also used as a starting point for traversing the main Yatsugatake ridge, linking Akadake and Yokodake. Its advantage is that many mountain huts make it easy to plan.
Editor's record
The editor's actual timings on this hike (from the video record). Use them as a guide to course times.
History & culture
Iwodake (Mt. Iou) is a 2,760 m peak in the southern part of the Yatsugatake range and one of the main summits that make up "Yatsugatake," one of Japan’s 100 Famous Mountains. Its greatest feature is the large explosion crater that gapes open on the north side of the summit. A horseshoe-shaped rock wall about 1 km in diameter and about 550 m deep vividly conveys the traces of ancient volcanic activity.
The summit area is broad and gentle, with superb views. It looks out at close range on the main Yatsugatake peaks such as Akadake, Yokodake and Amidadake, and on clear days you can see as far as the Southern Alps and Mt. Fuji. In winter the cairns standing along the trail serve as waymarks, and it is the season when the contrast between blue sky and white snow stands out most. On the other hand, above the treeline the wind is strong and winter-mountain experience and gear are indispensable.
Photos
All photos were taken by the editor on the actual hike. Tap to enlarge.
The snowy forest lit by morning light (around 2,370 m).
Following the snow ridge toward the summit dome of Iwodake (deep winter).
Standing on the snow ridge, the Yatsugatake peaks behind (near Akaiwa-no-atama).
The snow-clad peaks of the main Yatsugatake ridge.
Heading for the summit along a ridge with well-developed cornices.
Just below the summit, deep-winter gear (around 2,750 m).
Raising both arms on the summit of Iwodake, looking out over the main Yatsugatake ridge (2,760 m).
Standing on the snowy summit of Iwodake.FAQ
