Mt. Kamuiekuuchikaushi-yama (カムイエクウチカウシ山, Kamuiekuuchikaushi-yama) is a jagged peak standing in the innermost part of the Hidaka Mountains (日高山脈, Hidaka-sanmyaku). Its tall form, embracing both the Hachi-no-sawa Stream (八ノ沢, Hachi-no-sawa) and Koiboku cirque (コイボクカール, Koiboku-karu), can be seen from far and wide.
The name is an Ainu word meaning, somewhat inauspiciously, ‘mountain so steep a bear would tumble down it’. As the name is so long, it’s popularly called ‘Kamuieku’ (and that's what I'll call it as well).
This guide will take you up the Satsunai-gawa River (札内川, Satsunai-gawa) up to the Hachi-no-sawa River, a tributary of the former. The Hachi-no-sawa river gully will take you up to the summit. The climb up the Hachi-no-sawa is steep, and technical and more easily climbed by those with some experience in river-climbing (沢登り, sawa-nobori).
The halted construction of the Trans-Hidaka Road (日高横断路, Hidaka ondan-michi) has made the mountain much more accessible, but with increased accessibility comes an increase in the number of hikers and, consequently, incidents. You’ll want to leave a good margin of error and give yourself plenty of time to climb this mountain.
Generally, hikers reach the trailhead by private vehicle, or alternately rent a car at Obihiro Station (帯広駅, Obihiro-eki). From Nakasatsunai (中札内), you’ll pass Pyoutan-no-taki Falls (ピョウタンの 滝, Pyoutan-no-taki) and follow and road into the woods alongside the Satsunai-gawa River. About 1.2 km past Satsunai Hut (札内ヒュッテ, Satsunai-hyutte), you’ll find the trailhead at a parking lot with space for about 20 cars.
From the trailhead to Nana-no-sawa Stream confluence (七ノ沢出合, Nana-no-sawa deai), you’ll walk along an old forest road. Once you’ve reached the confluence, you’ll cross the Nana-no-sawa Stream and start to make your way towards Hachi-no-sawa Stream by walking up along the banks of the Satsunai. As you make the trip upstream you’ll walk along big dry riverbeds and through the forest of that borders the river. Since the headwaters of the Satsunai are so broad, this area could be a little difficult to navigate after heavy rains. It’s worth taking the extra time to find a place to cross safely.
You’ll camp at the Hachi-no-sawa confluence (八ノ沢出合, Hachi-no-sawa deai). Make sure to pack away your food and trash so that it doesn’t attract bears.
On the second day you’ll climb the Hachi-no-sawa ravine. On the long walk to Mitsumata (三股), an area at 1000 meters above sea level, you’ll probably find leftover snow near the top of the Hachi-no-sawa’s gradual slope as late as July. Make sure to watch your step as you climb so as not to fall through or cause a small avalanche. Onwards from Mitsumata the slope gets quite steep; you’ll be climbing among the waterfalls here so choose your steps carefully. The climb through here also sees a lot of rockfalls in the gully, so where possible try to walk along higher ground.
At the top of the ravine, you’ll be out of the Hachi-no-sawa stream and it’ll be time to climb up out of the cirque itself. The climb here is emblematic of the sort of hiking you’ll find in the Hidaka Mountains.
The Hachi-no-sawa cirque is quite wide and laid thick with Matsumura whitebeam and Peucedanum multivittatum. While the pika here are also numerous, this part of the mountain is well-known for being the Ezo bears’ (ヒグマ, higuma) feeding ground, so keep your wits about you. From the small campsite you’ll head left towards Pyramid Peak (ピラミッド峰, Piramiddo-mine), but just below the ridgeline you’ll turn right and climb up to the col.
You’ll make your way from the col up the steep ridgeline through fields of dwarf stone pine. When you make it to the top of the slim Kaiboku cirque on your left you’ll be quite near the summit. From the summit of Mt. Kamuiekuuchikaushi-yama you can look down at the southwest ridge (南西陵, nansei-ryou) jagged like the back of a dinosaur; to the north the mountain range stretches over the horizon. It’s a view that you could stand and look at forever. The bluffs of the summit are also home to the Ezo stoat—if you linger a while you might see one poke his head out in curiosity.
You'll head back down the way you came up. As you descend back to the col, you’ll probably be struck by how narrow Pyramid Peak looks before you. The descent below the col is quite steep and requires balance and care. You’ll descend all the way back to the Hachi-no-sawa confluence.
On the last day you’ll walk from the Hachi-no-sawa confluence back down the main branch of the Satsunai-gawa River. The trek back, through forests and across riverbeds, makes its was through a particularly luxuriant forest, even for the Hidaka Mountains. Listening for the echoes of woodpeckers knocking away at old trees, you’ll make your way back to the trailhead.
You’ll walk for a portion of this hike near the Trans-Hidaka Road (日高横断路, Hidaka Oudan-michi), a public works project that was cancelled well after construction had already begun. The project was started in 1994 and ended in 2003, a 19-year period over which the cost was ¥54 billion (for reference that’s $461.7 million USD in 2016). In 2003, with the project not nearly completed, the transport ministry decided to shut down funding. (The specific phrasing was “investment effect: none” (投資効果ナシ, toushi-kouka nashi)). The huge Satsunai Dam and sprawling road remain, however, changing the face of the Satsunai-gawa River forever. On the other side of the mountains, the Shizunai-gawa River (静内川, Shizunai-gawa), where the Trans-Hidaka round was supposed to connect, has suffered the same fate. A series of dams and eroded valleys line the useless road.
For the first half of the season the river will be quite swollen and there will be a large amount of snow remaining at the top of the Hachi-no-sawa cirque. The leaves start to change in mid-September.