Sengokuhara Bettei Fuga

Fuga is a small adults-only ryokan in Sengokuhara, part of the Gora hot-spring area. The main bath is split between an indoor pool and an open-air one, swapped between the men's and women's sides on a schedule, and the water is a clear, faintly salty chloride spring. All 10 detached Miyabi-tei rooms have their own semi-open-air onsen bath on the terrace, while a few rooms in the main building come with a private barrel sauna and a jacuzzi terrace instead (that jacuzzi runs on tap water, not the spring). Guests can also book a private open-air jacuzzi by the hour, and there's a rock-sauna room open to anyone staying. Children below junior-high age aren't accepted; it's built around quiet, adult time rather than family stays.