A 10-minute walk west of Kusatsu's Yubatake, at the far end of Sainokawara Park, lies one of Japan's largest open-air baths. Around 500 m² of pool brims with strongly acidic water, open to the surrounding forest. Snow in winter, fresh green in summer, illuminations at night. There are no washing stations — this is purely for soaking.
A large day facility where you can try Kusatsu's traditional 'awase-yu' — a row of wooden tubs at rising temperatures, entered in order. Indoor baths, rotenburo, sauna, plus rest and dining areas make it good for half a day. About 10 minutes' walk from the Yubatake, or a short bus ride. Admission ¥1,200 (2026); three-bath pass with Gozanoyu and Sainokawara ¥2,100.
Right in front of the Yubatake, a wooden recreation of the Edo–Meiji communal baths. Wood and stone bath halls alternate between men and women daily, with two sources (Yubatake and Bandaiko). The upstairs hall looks down on the Yubatake.
At 1,800 m, one of Japan's highest onsen. Milky water with some of the country's highest sulfur content, across nine tubs. Day use 10:00–17:00; prices rise in peak season.
A storehouse-style communal bath halfway up the 365-step stone stairway. Iron-rich brown 'golden water' in indoor tubs; rest hall upstairs. Cashless payment accepted.
The heart of Kusatsu, where 4,000 litres a minute cascade down wooden channels. The Yukemuri-tei pavilion beside it is a free 24-hour foot bath, lit up at night. Start your visit here.
A free communal bath right beside the Yubatake that welcomes visitors. Shirahata source water flows into two wooden tubs (hot and hotter). No soap, no showers — this is the locals' bath, so keep it quiet and quick.
The onsen hall of Kusatsu Onsen Hotel Village. Free-flowing source water in warm, hot and lie-down baths plus sauna for ¥930; add the swimsuit spa pool for families. The classic Kusatsu choice with kids.
A public open-air bath built right at Ikaho's spring source, above the stone-step street and Kajika Bridge. Nothing but bamboo-fenced outdoor pools where the rusty-brown 'golden water' flows straight from the source. Pair it with the bridge in autumn.
At 1,800 m in Manza, four private sources feed eight open-air pools of milky, yellow and clear water — the famous 'Sekitei' rock-garden baths. Mixed bathing, but gowns or wrapped towels are required and there is a women-only pool. Day use 11 am–6 pm (last 5 pm), ¥1,700.
A town-run day bath in the middle of the Minakami hot-spring street. Just one small indoor pool per gender, but 100% spring-fed sulfate water — an easy stop while strolling the town. Rest room, small shop and coin laundry give it the feel of a tourist office with a bath. 15 minutes on foot from Minakami Station. No soap provided.
Founded in 1691 and regarded as Japan's oldest surviving hot-spring inn building, this Shima Onsen institution in Gunma stands across a red bridge; the main house, said to be one of the models for the bathhouse in Spirited Away, is an Important Cultural Property. The celebrated Genroku-no-yu, built in 1930 in Taishō-romantic style, has five tubs set into a stone floor lit by arched windows, with water welling up from below. Shima's sulphate water is counted among Japan's three great baths for digestive ailments and can be drunk. Day use 10:00–17:30 (last entry 17:00), ¥1,500 with face towel, covering Genroku-no-yu, the mixed rock bath and private baths. Tattoos accepted if covered with stickers. About 40 minutes by bus from Nakanojō Station to the Shima Onsen terminus.
At 1,800 m in Manza Onsen — said to have the highest sulphur content in Japan — this is the most rustic of the old spa-cure inns. The wooden bathhouse holds just one indoor tub per gender, but the milky acidic sulphur water is thick and hot enough to leave you drowsy afterwards. It is known for its 'Sarunokoshikake-yu', in which extract of a bracket fungus has long been added to the water. Day use 10:00–16:00, ¥700 for adults, towels sold for ¥250. For onsen fans who want an old-school cure-bath feel amid Manza's big resort hotels. The building has tilted due to ground subsidence, so phone ahead to confirm it is operating. About 40 minutes by bus from Manza-Kazawaguchi Station.
The flagship hotel of Manza Onsen, which at 1,800 m is among the highest hot-spring resorts in Japan reachable by car all year. Perched on a rise, its famous 'Komakusa-no-yu' open-air bath juts from the mountainside so you soak in milky sulphur water while gazing at a sea of clouds, the Jōshin'etsu ranges and, in winter, unbroken snow — literally a bath above the clouds. Besides separate men's and women's sections there is a mixed zone where a wrap towel is worn, making this one of the few Manza inns where mixed bathing is possible. The sulphur content is among Japan's highest and the scent lingers after. Day bathing: adults ¥1,500, children ¥750, reception 11:00–16:00 (bath entry until 15:00), face towel included (bath towel hire ¥300). Weekdays are far quieter than weekends. About 2 hours by Seibu bus from Karuizawa Station, or about 40 minutes by bus from Manza-Kazawaguchi Station; direct ski-slope access in winter.