Mt. Oakan-dake (雄阿寒岳, Oakan-dake, lit. ‘Male Akan’) stands as the counterpart to Mt. Meakan-dake (雌阿寒岳, Meakan-dake, lit. ‘Female Akan’), standing across Lake Akan (阿寒湖, Akan-ko) to the southwest. The Ainu called Oakan Pinne-shiri, meaning ‘male mountain,’ while they called Meakan Matne-shiri, meaning ‘female mountain’. Proximity and similarly, it seems, has defined these two mountains since time immemorial.
As a side note, in almost all such male-female mountain pairs in Hokkaido, the male mountain is the smaller of the two (see also: Yotei (matne-shiri) and Shiribetsu-dake’s (Pinne-shiri)). Still Oakan cuts an impressive figure, being much more visible from the road and lake, looming over like some kind of guardian.
The trailhead sits near the Takiguchi Bus Stop (滝⼝バス停, Takiguchi basu-tei), 5 km to the east of Akan-kohan Onsen Village (阿寒湖畔温泉街, Akan-kohan onsen-gai). If you hit the junction with National Route 240, you’ve gone too far. Here on the southeast shores of Lake Akan, keep an eye open for the bent-over shapes of fishermen near the old floodgates near the beginning of the hike. The trail among the trees winds along the lakeshore, making for a picturesque walk; in fall the changing leaves reflected in the famously clear Akan water is a real sight to behold.
The trail will cross the new floodgates and turn towards the shores of Lake Taro (太郎湖, Tarou-ko). Water flows down the slopes above you and into the small lake, where it finds its way next into the Akan River (阿寒川, Akan-gawa), where it heads for Kushiro City (釧路市).
After leaving Lake Taro, the trail will head up into a forest of Sakhalin fir where you'll find Lake Jiro (次郎湖). The joke here is that 'Taro' is (or used to be, anyway), a common name for a first son; 'Jiro' means 'next son'.
After Lake Jiro, the track through the firs will begin to ascend among huge cliff faces in tighter and tighter turns. At the 2nd station marker (2合目, ni-goume) the trail will climb a steep slope and you’ll catch your first good glimpses of Lake Akan through the gaps in the Erman’s birch.
At the 5th station marker (五合目, go-goume) at 1194 meters above sea level, the trail will temporarily flatten off before reassuming the march for the summit. You’ll emerge from the forest to enormous views of Lake Akan, Meakan, and Fuppushi-dake (フップシ岳) across a sea of dwarf stone pine.
(By the by, Fuppushi-dake’s name comes from Ainu fupp-ushi, meaning ‘place where there is a lot of Sakhalin firs.’) You’ll also pass the ruins of an old army weather observatory.
After passing some very strange volcanic topography near the top of the mountain you’ll arrive at the summit of Oakan-dake. On a sunny day, peer down into the blackness of the evergreen forest on the backside of the mountain. Can you spot the little silver shapes of lakes Panketo (パンケトー) and Penketo (ペンケトー)?
You’ll head back down the way you came up. Keep your wits about you as you approach the 5th station marker, though — there’s a junction with the now-abandoned Okurushupe Trail (オクルシュペコース) around here, and it’s easy to wander off on it unawares.
There aren’t many flowers to be seen around here, but at the beginning of the summer you should be able to catch a glimpse of Canadian dwarf cornel. Along the upper part of the trail and especially in the depths of summer you’ll probably see a some cowberry and Empetrum nigrum. In the fall you should be able to see Campanula lasiocarpa. From mid-September onwards the changing leaves of the Katsura tree and the Japanese rowan are quite pretty; and the snow among the trees during any early winter ascent makes for a stunning hike.