The trail up to Kamihorokamettoku-yama (上ホロカメットク山), which sits between Mt. Tokachi-dake (十勝岳) and Mt. Furano-dake (富良野岳), is marked by the huge Ansei Crater (安政火口, Ansei-higuchi), which dances with steam rising from underground. The crater looks like something taken off a classical painted folded screen--a vista heightened only by the addition of snow.
The mountain's name, too, is shrouded somewhat--one theory contends that the mountain here was called Penakushihorukamettok in Ainu--a mouthful meaning 'the upper part of the river which winds back upon itself at a mountain.' No one's certain what this could be referring to, but it might indicate the headwaters of the Tokachi River (十勝川, Tokachi-gawa), which lies nearby. The other mountain, Mt. Furano-dake, is alone among the Tokachi Mountains in being covered thickly in alpine vegetation, and bears a name not nearly so apocryphal: it comes from the Ainu hura-nu-i, meaning 'river carrying a foul smell.'
Leaving Tokachi-dake Onsen (十勝岳温泉), you'll head towards Ansei Crater along a relatively gentle trail. Along the way the trail will break off towards Mt. Sandan-yama (三段山) through a forest of dwarf stone pine. To get to Mt. Kamihorokamettoku-yama you'll cross the valley before Ansei Crater and come to a junction on the lower limns of what's known locally as the D Ridge (D尾根, d-one). Here you'll arrive at *Kamihoro Junction (上ホロ分岐), where the trail splits towards a long traverse directly to Mt. Furano-dake.
Climbing the steep slope of D Ridge here you'll be able to catch views of the whole ridgeline running to Mt. Tokachi-dake in the north, if you're lucky. As you climb up onto the ridge, you'll more than likely see some blue heath and Aleutian avens growing near your feet. In recent years, the 1893-meter peak at the neck of D Ridge has been christened Mt. Kamifurano-dake (上富良野岳).
From Mt. Kamifurano-dake, a 20-minute walk will bring you to the summit of Mt. Kamihorokamettoku-yama. From the summit you should be able to see Mt. Tokachi-dake along the ridgeline to the north; continue along the ridgeline to south and west you'll see the rocky form of Mt. Furano-dake. Across the summit and below somewhat is the mountain hut called Kami-horo Lodge (上ホロ避難小屋, Kamihoro hinan-goya). You'll find it near the northern junction with the trail that rings around the east flank of the summit.
Head back to Mt. Kamifurano-dake and continue towards Mt. Sanpou-zan (三峰山). The ridgeline will widen into a broad rocky field here, dropping gradually into an 1803-meter col. The sharp mountain you'll see to the east is Sakai-yama (境山). Featuring no trails to be trod in summer, the massif looms silently. Along the col between Mt. Sanpou-zan and Furano-dake you'll find more Aleutian avens, along with some Stellar's veronica. Besides the flora, it's not unheard of to come across a bear munching on the fruit of the dwarf stone pine. Mt. Furano-dake is noted for being the habitat of a good number of bears, so be wary of leaving garbage or food behind.
From the Traverse Junction (縦走路分岐, Juusou-ro bunki) onwards to the summit the trail gets quite steep and rocky. As the ridgeline narrows you'll see Narcissus-flowered anemone, Japanese bluebells, and hawksbeard, among others. From the summit of Mt. Furano-dake you can see out to Genshi-ga-hara Marsh (原始ヶ原) at the foot of the mountain, as well as out to the massif of Mt. Ashibetsu-dake (芦別岳)across the valley.
Heading back to Tokachi-dake Onsen, you'll return to the Traverse Junction and descend along a long traverse through low shrubbery. After you pass over two ravines, you'll shortly come to Kamihoro Junction at the foot of D Ridge.
After following the gentle trail you took in for a little under an hour, you'll arrive back at Tokachi-dake Onsen.
Along the ridgeline from Sanpou-zan to Mt. Furano-dake, flowers will bloom wildly around mid-July. In the vicinity you'll also find wedgeleaf primrose and Japanese bluebells. The leaves start changing color around mid-September. Around this time as well it will start getting quite cold, so you're going to want to bring some cold- weather gear.