Shari-dake is a mid-sized mountain in Eastern Hokkaido, not far from the village with the same name. The mountain is one of the 100 famous mountains of Japan and therefore attracts many climbers throughout the year.
The trailhead is located at the Seigaku-so 清岳荘 hut, which also has a parking place. As always in Japan, I would recommend being early, as parking places are getting crowded very fast. You will be asked by a sign to pay 100yen at a small box right at the trailhead for as parking fee. After this, head onto the trail and after a short passage downwards, you will walk along a forest road until the path goes back into the forest to the left side.
From here, you will basically follow the flow of the river uphill. The river has to be crossed multiple times and it can be a little bit wet. It gradually becomes more steep and after a while, you will arrive at a junction where you have two options, follow the the old route to the left, or take the new route to the right.
It is noteworthy that the old route is quite steep and continues along the water, so it is extremely slippery at times. The new route is taking quite a detour but is significant less dangerous. I would say that if you are a seasoned mountaineer, ascending via the old route should be doable, but I would definitely recommend descending via the new route, as it does lead away from the waterfalls and is therefore less slippery. My guess is that the new route has been established to ease the descent, as there might have been a number of accidents on the old route with these conditions.
After the waterfall passage (which is undeniably the most difficult part of this hike), you will at some point arrive at a plain and shortly after that, you will see the junction that brings the old route and the new route back together. From there, just head straight and climb up to a small plateau with moderate views. From here you can already see the summit to the left. Follow the signs to the left and there will be a short rocky section until you arrive at the Shari-dake Shrine 斜里岳神社, which is a really small shrine just below the summit. From there, follow the path and you reach the summit in about 5 minutes.
The views from Shari-dake are breathtaking. With good weather, the mountain provides 360 degree views of the surroundings, including Shari village, the Sea of Ohotsk, the Shiretoko Peninsula, Abashiri, etc. To the other side, you can also see the silhouettes of the mountains in the Daisetsu-san National Park.
When descending, follow the path down where you came from until you reach the junction where the old and the new route merged again. This time, take the new route to the left towards Kumami-toge (bear view pass). This route will lead over the ridgeline to Kumami-toge and then descends down back to where the waterfalls where.
Speaking of bears. While there are certainly bears in Hokkaido (the native bear is the brown bear ヒグマ, the possibility to actually see one is extremely low. On the Kumami-toge, we met an older Gentlemen who lives in the area of 77 years who told us that on this day (September 21, 2020) this would be his exact 900st attempt to the summit of Shari-dake. That is quite an accomplishment, and he wanted to continue until he reaches 1000 summits of Shari-dake. The stunning part however was that in all these 900 summits, he has never seen a single bear (!).