Bōkorō

This ryokan has stood on the shore of Lake Togo since 1931. A red bridge runs out from the building to its signature bath, an open-air tub built right over the lake, with nothing between you and the water view. Indoors there's a large bath (one of the bigger ones in the area) plus a sauna and a cold plunge, and the water throughout, including in the in-room baths of its private guest wing, is kept flowing straight from the source. The two main baths aren't mixed; they swap between men and women through the day rather than running side by side. Day-use bathing isn't offered here, it's for overnight guests only.