Onsen and baths in Katashina

A polished modern day-use onsen resort near Oze in Katashina village, with mountain-view outdoor baths, a hot sauna and cold plunge, rock-bed sauna, restaurant, and garden grounds.

A roadside day-use bath near Nikko-Shirane popular with skiers and hikers, with one indoor and two large kakenagashi outdoor baths (no chlorination or recirculation) around 41-42C, heated changing-room floors, and a lounge, though several reviewers report a slippery mossy floor and bugs in the outdoor bath, and the soba restaurant several reviews mention no longer seems to be open.

A small, cash-only day-use-only bathhouse near Oze with a single indoor sulfur-smelling tub and no sauna, cold bath, outdoor bath or restaurant, popular with hikers and skiers despite recurring complaints about rude front-desk staff.

A tiny, TEPCO-run day-use bath attached to the Oze Nature Center at Tokura, popular with hikers waiting for the bus, with genuine kakenagashi alkaline sulfur spring water and full amenities but a very small tub that fills up fast at peak hiking-season and bus-arrival times.

A remote, single lodge-style ryokan (environmental resort) on the shore of Lake Marunuma, with a distinctive bath overlooking a fish tank of trout and char; day-use bathing is offered but only during narrow, inconsistently-enforced afternoon hours.

A beloved lukewarm 100% natural kakenagashi hot spring inn near Oze, prized by hikers and skiers for its unheated, unrecirculated, chlorine-free alkaline water in one indoor and one outdoor tub.

A ropeway-station bathhouse at Marunuma Kogen near Nikko-Shiranesan with rust-red, iron/sulfur turbid water and a sauna but no outdoor bath, popular with hikers and skiers; one reviewer notes staff said traditional tattoos are welcome, but only one review confirms this.

A stylish manga-cafe/lounge-and-onsen hybrid inside the Oze Iwakura ski resort hotel, run by the 'ofuro cafe' chain, offering kakenagashi alkaline sulfur water, a large book library, kids area, and unlimited alcoholic drinks, though one reviewer found the bath itself small and dated.

Baths that admit you without an overnight stay

Rotenburo, confirmed by visitors

Gensen kakenagashi, not recirculated

Often with a cold plunge