Mount Asama

Asama is the 2,568-meter volcano smoking behind Karuizawa, and the Japan Meteorological Agency monitors it around the clock. How far you can climb depends on its eruption alert level. The crater itself is always off-limits: even at Level 1, the lowest, nobody may go within 500 meters of it, and the closest you can get is Maekake-yama, 2,524 meters. That route starts at Tengu Onsen Asama-sanso and runs via the Kazan-kan hut and the Sai-no-kawara junction; the round trip takes about 6 hours 40 minutes with roughly 1,100 meters of climbing. At Level 2 it closes, and the usual goal becomes Kurofu-yama, 2,404 meters, the highest point of the old outer rim, about 3 hours 10 minutes there and back from Kurumazaka-toge. From Tomi-no-kashira and Kurofu-yama you look across a caldera floor straight at the cone, a view many prefer to Maekake's. The level went up to 2 in March 2023 and back down to 1 on 22 May 2026, so check the JMA and Komoro City notices before you set out. Wear a helmet (free loans at Asama-sanso, Takamine Kogen Hotel, the Takamine Kogen visitor center and Kazan-kan), drop a climbing plan in the trailhead box and carry a bear bell. On the Gunma side, Onioshidashi Park is a field of black lava from the 1783 eruption.