The source at Mizusawa was found in 1889, somewhere on the flanks of Akita Komagatake, and the water has been running since then without particular ceremony. Sulfurous, direct, the kind of water that announces itself before you reach the bath. The onsen-go sits in a narrow highland corridor between Tazawako and Nyuto Onsen-go, neither quite one thing nor another — not a lakeside retreat, not a deep-forest hermitage, but something of both, held together by the smell of sulfur and the steady presence of the mountain above.

The Oku-Mizusawa source feeds both Mizusawa Sanso and the self-catering facility nearby, where day visitors come and go without much fuss. Staying several nights here, one begins to feel the rhythm that drives the place: hikers in one season, skiers since 1969 when the slopes opened, the mountain lending a different character to each. There is something almost provisional about a resort that answers honestly to two calendars, that never quite settles into a single identity. The accommodation is plain in the way that mountain places often are — the point is never the room.

Route 341 brings you in from the Tazawako station bus, thirty minutes of gradual ascent. That small increment of altitude matters. By the time you arrive, the valley world has receded enough that you notice the quiet rather than seek it. The water does the rest — sulfur-edged, immediate, uncomplicated — and several evenings in the bath with the mountain somewhere above in the dark is, it turns out, quite enough.