Mt Sekison

Mt Sekison (Japanese: 石尊山) rises quietly above the resort town of Karuizawa, a modest peak shaped by its close proximity to the active volcano of Mt Asama (浅間山). Sekison sits like a small outpost on Asama’s southeastern flank, a forested shoulder that catches the volcanic mountain’s light, weather and moods. The topography reflects this closeness with broad lower slopes, a steady climb through the forest, and then a final steep pull that feels like stepping onto a balcony facing Asama itself. Many people use Sekison as an alternative at the times when its neighbour is declared out of bounds due to volcanic activity.

​

The hike begins in the resort area, where paved lanes and villas gradually give way to forest. The hike begins with a steady climb through quiet woods where the air feels cooler and the sounds of Karuizawa fade behind you. As you gain height, the trail leads to the Chi no Kawa “river of blood,” which is a striking red‑stained gully carved by mineral‑rich runoff. It’s an unexpected splash of colour in an otherwise green landscape.

​

From there, the climb steepens. The final ascent to the summit is short but sharp. Mt Asama fills the view with its slopes rising in a single powerful and distinctly volcanic sweep. To the south you can see the Yatsugatake range (八ヶ岳) and to the southeast the mountains of Gunma

​

Autumn is perhaps the best season to visit. The forests around Sekison turn brilliant shades of gold and crimson, and the crisp air makes the steady climb feel refreshing rather than demanding. It’s a relatively small mountain, but one that offers a surprisingly rich blend of scenery, geology, and seasonal colour.

​

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