This blog post was written back in 2008. For the latest information about this hike (including color photos and maps), please consider purchasing my guidebook to the Japan Alps.
Mt. Jonen is a wonderful alpine peak located just across the valley from Hotaka mountain range and Kamikochi. Sunrise and sunset are magical.
The hike: From the parking lot, walk 4 km on a heavily damaged forest road until reaching the trailhead at Hiedaira (ヒエ平). The road was completely washed out in flooding a few years ago, and if they’ve re-opened it then you can save 8km of easy round-trip hiking. The trail starts off quite flat, following the Ichinosawa (一ノ沢) river upstream to its source. You’ll cross a few tributaries coming off the right side before the real climb begins. It should take about 3 or 3-1/2 hours of hiking along the river before reaching the final steep climb to the ridge line. You’ll know you’ve reached the point when the trail crosses a tributary and starts switching back quite rapidly. Make sure you fill your water bottle at the stream. It should take about an hour of steep climbing before reaching the ridge. Ther’ll be a massive hut greeting you, with the trail to the top of Mt. Jonen branching off to the left. The hut is called Jonengoya (常念小屋) and it’s a good place for a snack break. There’s a descent sized campground here, as well as some toilets. The views toward Mt. Yari and Hotaka are stunning. From the hut, the trail zigzags for about an hour before reaching the summit. The views are incredible if the weather is clear. For some reason, the fog seems to come in very quickly on this shy peak. There are 2 trails branching off from the top, but head back to the hut unless you’d like to traverse onward to Kamikochi. You can either head back down the way you came, stay at the hut, or continue on the ridge line to either Mt. Tsubakuro or Mt. Yari. The extensive network of ridge trails make for an interesting couple of days exploring the beauty of the Kita Alps.
When to go: This hike is popular from Golden Week to early November. Although not impossible, a winter hike requires experience and equipment, but neighboring Mt. Tsubakuro (燕岳) is popular for winter climbing, so a ridge traverse is quite feasible.
Access: While there are a number of approaches to this peak (including from Kamikochi), the hike described here is only accessible by car or taxi, and the forest road may still be closed to vehicular traffic. The nearest station is Toyoshina (豊科駅), on the JR Ooito Line (大糸線) conecting Matsumoto to Hakuba stations. The forest road to the trailhead at Hiedaira (ヒエ平) was closed at the time of writing, which means you’ve got an extra 4km of hiking from the parking lot to the trailhead, so get an early start.
Level of difficulty: 4 out of 5 (elevation change ~1500m)
Hiking in Japan 