The Hidaka Mountains (日高山脈, Hidaka-sanmyaku) run from Karikachi Pass (狩勝峠, Karikachi-touge) to Cape Erimo (襟裳岬, Erimo-misaki). Locals call them 'The Spine of Hokkaido', and a cursory look at a terrain map will reveal why. The largest of these mountains, Mt. Poroshiri-dake (幌尻岳, Poroshiri-dake), spreads its arms around an ice-age glacial cirque; its name comes from the Ainu poro sir, which means 'huge mountain.' This is, you will find, appropriate. Mt. Tottabetsu-dake (戸蔦別岳, Tottabetsu-dake) divides Poroshiri's cirque from the Nanatsu Marsh cirque (七ツ沼, Nanatsu-numa), and stands opposite, as if in attack. On the slopes of Tottabetsu is the Tottabetsu River (戸蔦別川, Tottabetsu-gawa), and at the base of its remarkable cirque sits the exposed form of Kanran Bluff (カンラン岩, Kanran-iwa). It's said that the Tottabetsu River gets its name from Ainu totta pet, meaning 'box-shaped river.'
Two trails lead up to the summit of Poroshiri-dake: from the Nukabira River (糠平川, Nukabira-gawa) in the west, and from the Niikappu River (新冠川, Niikappu-gawa) in the south. In this guide you'll head up the Nukabira River, stop for a night at Poroshiri Lodge (幌尻山荘, Poroshiri-sansou) before crossing the summit. Fewer people climb here than elsewhere in Hokkaido, so nature still appears as it has been for thousands of years. For the first half of the climb, you'll want to bring shoes for river-walking, if you've got them. The early part of the trail follows the river itself, and after rains or for the first half of the summer, high water will force you to wade through the river itself in places.
From National Route 237 (国道237号線, Kokudou 237 gosen) in the Furenai District (振内) of Biratori Town (平取町, Biratori-chou), head towards Toyonuka (豊糠) and follow the Nukabira River along a forest road. When you hit the gate across the road, you'll have reached the trailhead. You'll have to walk from here to Shussui Dam (取水ダム, Shussui-damu), 7.5 km further along this old logging road.
From the dam you'll continue along the right bank of the Nukabira River. Heading around a small bend, you'll shortly arrive at the confluence of the river and the Yon-no-sawa (四ノ沢) and proceed up the river, crossing back and forth between the banks until you've arrived at Poroshiri Lodge. If you keep your eyes peeled for crossing points on the other side of the river as you hike, it shouldn't be too tough to find them. Since Poroshiri-dake was chosen as one of the "One Hundred Famous Mountains of Japan," a larger number of novice hikers have been coming here, but that doesn't mean that Poroshiri-dake will give up her summit easily. This is a trip better suited to experienced hikers.
Staying at Poroshiri Lodge requires a reservation beforehand. There are no cooking facilities, so bring your own cookware. In August there may be a manager stationed there. In summer, it can get quite busy, so it's a good idea to sort out your lodging well beforehand. Furthermore, since there are a good number of bears in the area, please store and manage your garbage responsibly.
From Poroshiri Lodge the trail heads up a steep forested slope. In the fall the changing leaves make this part of the hike especially beautiful. Just before the bounds of the forest, on the left, you'll come across Inochi-no-mizu (命の水), where you can refill on water. The forest will give way to a low field of dwarf stone pine and you'll emerge onto the main ridgeline to the summit. Looking north, you should be able to see the huge bowl of the North Cirque (北カール, Kita-kaaru).
Following the rim of the cirque you'll proceed slowly up to the summit. The grassy fields and scrubby pine forest are among Poroshiri-dake's bears' favorite feeding grounds, so keep an eye out.
Multicolored flowers also bloom all along here during the early summer. If you've got an eye for it, you can spot Aleutian avens, Alaskan arnica, blue heath and Japanese gentian.
Soon after meeting the Niikappu Trail (新冠コース, Niikappu-kousu) coming from the south, you'll arrive at the summit of Poroshiri-dake. Amid the crowded mountains all dashing up against you, it's easy to lose track of time in the view. You've still got a ways to go ahead, so don't spend too much time up here.
The ridge across to Tottabetsu-dake is even more windswept than hitherto, so if the weather or if your own strength is in doubt, consider well going back to Poroshiri Lodge so as not to lose your way on the massif.
Up off the shoulder of Poroshiri-dake is fairly level, but as you enter the upper part of the Nanatsu-numa cirque the slope becomes quite steep. Tread carefully here. Crossing the narrow Tsuri Ridge (吊尾根, Tsuri-one) at the upper part of the cirque towards the summit of Tottabetsu-dake you'll climb up a steep slope.
Standing at the summit of Tottabetsu-dake, you can look across the Niikappu River valley at the distant peaks of Esaomantottabetsu-dake and Kamuiekuuchikaushi-dake (both exciting, and descriptive, names from the Ainu language).
From Tottabetsu-dake to the 1881-meter traverse junction you'll be able to see flowers such as Potentilla matsumurae, Saussurea chionophylla, and Pedicularis apodochila blooming in the breeze. At the junction a trail splits off to Mt. Kita-tottabetsu-dake; but head instead back down towards Poroshiri Lodge. The slope is steep and long so grit your teeth and steel your knees.
When you arrive at Roku-no-sawa (六ノ沢), feel free to drink the delicious water there (after filtering of course). From there onwards you'll wade down the stream, through the forest, and back to Poroshiri Lodge.
Take your time at the lodge and rest up before heading back down the Nukabira River towards the trailhead on the forest road. If you happen to be climbing in the fall, take a moment to appreciate the yellow leaves on the katsura trees (桂木) -- they're especially beautiful on the forest road out.
Until about mid-July there will still be a lot of snow melting in the cirques. The flowers will be blooming between late- July and into August. The leaves start changing around mid- September. In the fall, the water in the stream can get quite cold.