Nuru-yu: The Gentle Baths

A remote ryokan on Lake Shikotsu whose signature bath is separated from the lake by nothing but rock, plus a view rotenburo, indoor baths with sauna, and two private baths.

A small mountain ryokan in Kuji known for its strong alkaline spring water, with a big indoor bath at two temperatures, an open-air bath, a source-water cold plunge, and a sauna, all open to day visitors.

A deep-valley ryokan at Shiobara Motoyu known for the Sumi-no-yu, a sulfur bath that turns coal black and shifts color with the weather.

A cozy, old-fashioned ryokan in Shima Onsen where every bath, indoor and outdoor, is fed by real onsen water, including three private baths free for guests to use as often as they like.

Shimobe Onsen has a long association with Takeda Shingen, who allegedly used these cold springs to treat battle wounds, and the alternating hot-and-cold soak that Hashimotoya still practices is said to go back to that tradition. The cold spring here comes out at around 32°C naturally, paired with a drilled hot spring at 50°C, so you move between the two. It's one of only a handful of places in Japan where you can still do this kind of therapeutic cold-mineral-spring bathing.

The senninburo at Kanaya Ryokan is, by common account, the largest all-hinoki (cypress) bath in Japan. Built in 1915 (Taisho 4), the vast wooden hall stretches roughly 20 metres and bathes you in the clean, warm scent of cypress throughout. It is a mixed bath (konyoku): women can also enter a connected women's bath and benefit from women-only hours. The ryokan itself was established in 1867 in Izu, Shizuoka, tucked in a quiet valley with spring water flowing directly from the base of Kanaya Mountain. Beyond the great hall, there is also a small outdoor rotenburo for those who want open sky. The combination of hot spring water, cypress, and a 160-year-old inn is genuinely hard to find elsewhere.

One of the best-known lukewarm baths in Izu, in the hills of Izunokuni. Everything here runs kakenagashi straight from a 38°C spring, and the tubs are held at a spread of temperatures from about 36°C up to 41°C, so you pick the one you want and stay in the cool end as long as you like. There is a waterfall bath (utaseyu, 打たせ湯) as well.

One of Kinosaki Onsen's seven public baths, with a hot indoor tub, a shallow pool for small children, and a Jizo statue enshrined at its spring source.

A small neighborhood bathhouse near Dogo Onsen in Matsuyama, known for soft, faintly slippery spring water and a local earthquake legend tied to its source.

A tiny hot-spring ryokan built around a lukewarm cave bath that's been flowing for over 300 years, with a women-only cave bath and two reservable private baths alongside it.