Mt Kurofu &
Mt Jakotsu

Mt Kurofu (Japanese: 黒斑山) and Mt Jakotsu (蛇骨山) form part of the dramatic caldera rim of Mt Asama (浅間山), offering one of the most rewarding ridge hikes in the region. The most convenient starting point is Takamine Kōgen on Kurumazaka Pass, where a small parking area gives direct access to the forested slopes. From here, the trail climbs steadily and sometimes steeply  quiet woodland. After a couple of hours, the trees thin and the breathtaking bulk of Mt Asama comes into view, its volcanic flanks rising sharply across the valley.

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Mt Kurofu itself is a forested peak with limited views from the summit, but the scenery before and after the peak is superb. For me, the real highlight begins when you continue along the so‑called J‑band ridge toward Mt. Jakotsu where the number of hikers decline. The cliffs here are sheer and dramatic, dropping away into deep valleys, and the views of Asama’s volcanic landscape are spectacular. Care is essential because this section is exposed, and a slip would be serious.

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At the far end of the ridge lies Mt Nokogiri (鋸山), where Asama’s full volcanic splendour stands directly before you. In winter, this entire route becomes a beautiful and atmospheric hike, provided you have proper equipment for snow and ice. When there is no snow, an excellent loop is possible: from Nokogiri, you can descend into the valley below and climb back up the Kusa‑Suberi course to Mt. Kurofu. This ascent is not possible in winter, and a helmet is strongly advised due to rockfall risk in one section.

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I’ve found this caldera‑rim traverse to be one of the most striking hikes near Asama. It's rich in volcanic scenery, varied terrain and unforgettable views.

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(All information here is based on personal observations and experiences. Check official sources before planning or starting any hikes.)