To reach Oku-Kinugawa, you travel ninety-five minutes by local bus from the railway at Kinugawa Onsen to Meotobuchi, and then — the road having run out of ambition — you continue by shuttle or on foot for another hour or so along a forestry track into the headwaters of the Kinu River. The gorge narrows. Waterfalls appear where tributaries lose their footing. The four inns that constitute this onsen settlement — Kaniyu, Teshirosawa, Nikkosawa, Hacho no Yu — are each solitary establishments, separated from one another by forest and stream, each drawing from its own springs. Kaniyu alone claims five distinct sources; Hacho no Yu, eight. The waters arrive from different seams in the earth, and to stay several nights is to begin sensing the differences between them, the way one might distinguish voices in a chorus.

The settlement took shape in the early Shōwa era, though it remained genuinely remote until electrification came in 1986 and the forestry road opened two years later. Even now, the infrastructure feels provisional, as if the mountains had agreed only reluctantly to let it stay. Teshirosawa does not accept day visitors at all — you sleep there, or you do not enter. This is not exclusivity so much as a kind of quietness made structural: the inn exists for those who have committed to the walk and the night.

What you find, after the long approach, is a gorge country of high marshland and steep slopes where the river is still young and cold. The rhythm here is set by the water — falling over rock, rising warm from the ground, filling wooden tubs that feel as though they have always been there. After two or three days, the bus ride back to the railway begins to seem like a longer journey than the one that brought you in.