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.
Hokkaido's flagship onsen ryokan: a vast 5,000 m² bathhouse overlooking Jigokudani with 35 tubs fed by five spring types — sulfur, salt, sulfate and more. Day bathing is accepted from 9:00 to 18:00. An indoor heated pool makes it good for families. Tattoos not permitted.
The oldest inn in the Nyuto Onsen area, a hidden hot spring dating to the Edo period. The thatched 'Honjin' building and the large milky-white mixed rotenburo are its iconic scene. Day bathing 10:00–15:00; on Mondays the rotenburo is closed for cleaning and only indoor baths are open. Rooms sell out months ahead. From Tazawako Station take the bus, then the inn shuttle from Alpa Komakusa.
A Meiji-era inn at the entrance to the Jigokudani Monkey Park, famous worldwide for wild macaques that climb into its rotenburo in winter. Day bathing is only 12:00–15:00, so most visitors combine it with the monkey park. It's a 30-minute mountain trail from Shibu Onsen — wear grippy shoes in winter.
The centerpiece of Nozawa's 13 public baths, a traditional bathhouse in the middle of the village. Local 'yunakama' associations have cleaned it daily since the Edo period; payment is a donation in the box at the door. Two pools, hot and 'mild' — though even the mild one exceeds 42°C. Adding cold water is bad manners: rinse first, then keep soaks short. No soap or shampoo.
In the Hakkoda mountains, bathing since 1684 and Japan's first National Recuperation Onsen. A vast all-cypress mixed bath hall (about 260 m²) fed by four sources. Women-only hour 8–9 am daily; bathing garments sold on site.
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.
The signature inn of Shirahone, famous for milky-white water. Its highlight is a large mixed-gender open-air bath — the water is so opaque that women find it comfortable. Day use at midday only.
The largest day-use facility in Okuhida. Sixteen open-air pools (7 men's, 9 women's) scattered through the forest, all fed directly from the source. Hida beef restaurant on site. The classic stop after Kamikochi or Shin-Hotaka.
A large hotel whose top-floor 'sky' open-air baths look over the Noboribetsu hills. Day use in two windows — 5–9 am and 11 am–7 pm — for ¥1,200. A little away from the main strip, so quieter.
A free foot bath in an actual river of hot spring water flowing out of Ōyunuma pond, at the end of a forest boardwalk. The perfect finish to a Jigokudani walk. Daylight hours; the trail may close in deep snow.
A Kengo Kuma-designed communal bath at the entrance to Ginzan's Taishō-era street. Hot water with drifting mineral flakes for ¥500. The one place day visitors can bathe in Ginzan's water — reception closes at 3:30 pm.
The large ryokan at the entrance to Ginzan. Indoor, open-air and lie-down outdoor baths — far roomier than Shirogane-yu. Day use 11:30 am–2 pm (last 1:30), ¥1,500, closed Thursdays; day bathing has been suspended and resumed repeatedly, so check the website. Cash only.
A locals' public bath three minutes from the east exit of Echigo-Yuzawa Station, tucked into the shopping street. Indoor pool only, but the slightly hot, soft water that clings to the skin gets praise. Shampoo is provided and a towel set costs ¥400, so you can drop in empty-handed while waiting for the shinkansen. ¥600 since December 2025.
A wooden toji (therapeutic stay) inn over 200 years old on the Toyosawa River in the Hanamaki-Minami onsen area, once frequented by poet Kenji Miyazawa. Its signature is 'Osawa-no-yu', a mixed open-air bath jutting over the river, with women-only hours. Day bathing from 7 am; ¥700 covers three baths. Many linger for lunch and sake at the 'Yahagi' dining room. Free shuttle from Hanamaki Station.
Three minutes by car from Yamanakako IC, a day spa with Mt. Fuji rising straight ahead of the open-air bath. Highly alkaline (pH 10.3) yet gentle on the skin. Two open-air baths—stone and cypress—plus a lie-down bath, jets and sauna for ¥900. On winter weekends (Dec–Feb) it opens at dawn so you can watch the peak blush red at sunrise, the 'benifuji' of its name. 30 minutes from Fujisan Station on the Fujikko-gō loop bus.
The public day bath at the heart of Matsunoyama, counted with Arima and Kusatsu among Japan's 'three great medicinal springs'. The water is fossil seawater some 12 million years old, heated geothermally — salty, slightly oily and hot enough to warm you to the core. Indoor bath plus a small open-air tub, ¥600 (¥500 after 17:00). In this heavy-snow region it becomes a snow bath in winter. Used by inn guests for bath-hopping too, and close to the site of the famous 'groom-tossing' festival.
A lone inn at 1,300 m, the last stop in the Nasu hot-spring range. Spring water gushes out behind the building in such volume that it forms a river, dammed into the vast outdoor 'Kawa-no-yu' — nothing else like it in Japan. Mixed bathing since the inn's founding, but bathing wear is included so beginners can relax. Day use is limited to three hours (reception 11:30–14:30), ¥1,300 with face towel and bathing wear. The outdoor bath closes in bad weather or for cleaning, so phone ahead. Autumn colour and snow seasons are the draw.
At Kawayu, where 73°C spring water bubbles up through the bed of the Ōtō River, a giant outdoor bath is created every December to February by damming the river. Roughly 50 by 15 metres — big enough for 'a thousand people', as the name says — it's tempered to perfection by the river's cold flow. Free (donation box), 6:30–22:00, swimwear required, open to everyone. Bathing is suspended in bad weather or high water and opening dates shift from year to year. In summer you can dig your own pool in the gravel. Combine with Yunomine and Watarase for the three Hongu baths.
A single inn at the end of the Nyūtō bus line, wrapped in old-growth beech forest and named for the river crabs once abundant in the nearby stream. Unusually for Nyūtō, the water is clear and colourless — a bicarbonate spring with drifting white flakes and a gentle feel. The signature is Karako-no-yu, a mixed open-air pool some 50 m from the building in the woods, magical in snow season; there are also separate indoor wooden and rock baths. Day use 9:00–16:30, ¥800. Covered by the Yumeguri-chō pass (¥2,500, valid one year) for all seven Nyūtō inns — the classic combo is with Tsuru-no-yu and Taenoyu. About 50 minutes by bus from Tazawako Station to the Nyūtō Onsen stop.
A mountain hot spring in the temple-gate village of Kurama, about 30 minutes from central Kyoto on the Eizan railway, home of the tengu legends. The open-air Hōroku-yu sits in a cedar grove facing the Kitayama hills and becomes a snow-viewing bath in winter. The simple hydrogen-sulphide water carries a faint whiff of sulphur that suits the mountain air. The open-air-only course is ¥1,500 weekdays / ¥1,600 weekends (towels extra); the full day course with indoor bath, open-air bath, sauna, lounge, towels and robe is around ¥2,600 on weekdays. Open 10:00–21:00 every day, no reservation. Ten minutes on foot from Kurama Station or by free shuttle. The classic way to end a visit to Kurama-dera or the hike over to Kibune — for anyone who wants a genuine onsen in Kyoto.
An open-air-only public bath on the gravel banks of the Gamata River at Tochio Onsen in the Okuhida valley. The rock-ringed men's and women's pools have no screen on the river side, so the rushing Gamata and the Northern Alps fill the view — starry skies at night, snow scenes in winter, wild Okuhida all year. Free-flowing simple spring water; there are changing huts but no reception — drop a donation (about ¥300) in the wooden box at the entrance. Open 8:00–22:00 (from 12:00 Mon, Wed and Fri for cleaning); no closing days, but suspended when the river is high. Bring a towel. An easy stop between the Shinhotaka Ropeway and Hirayu, or a night soak for anyone staying in Tochio's inns.
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.
About 12 minutes on foot from Murodō terminal, the hub of the Tateyama-Kurobe Alpine Route, this inn at 2,410 m is Japan's highest hot-spring lodging. Milky acidic sulphur water piped from Jigokudani flows 100% free, and outside the window is another world: the 3,000-metre Tateyama range and the volcanic lake Mikurigaike. The bath is indoor only; day use 09:00–16:00, ¥1,100 for adults. The café's blueberry soft-serve and curry are favourites. Open only during the mountain season, mid-April to late November; closed in winter. Especially busy during the Snow Corridor (Apr–Jun) and autumn colours (late Sep–early Oct). With the altitude and strong water, keep your soak short.
A lone inn of the Japan Association of Secluded Hot Springs, deep in Hachimantai National Park amid beech and oak forest. The open-air bath is an unusual greenish milky white — free-flowing simple hydrogen-sulphide water — with a mixed outdoor bath, a women-only outdoor bath and separate indoor baths; from the rotenburo you can see the steam of Japan's first geothermal power station. Day use 08:30–19:00 (last entry 18:00), ¥700 for adults, or ¥900 with hall rest 10:00–15:00. Open year-round, and the snow-buried outdoor bath in winter is the highlight. About 1 h 50 min by Iwate Kenpoku bus from Morioka Station to the Matsukawa Onsen terminus.
Hijiori Onsen, 1,200 years old, is a cure-spa where inns huddle at the bottom of a caldera in Ōkura village, Yamagata. Right in the middle of the street stands Kami-no-yu, the only communal bath open to visitors. A small bathhouse with an attendant's counter, it has slightly hot free-flowing sodium-chloride/bicarbonate water and a tiny Yakushi shrine in the corner of the tub. Adults pay ¥400 (free for guests of the village inns); open 08:00–18:00 (until 17:00 in winter), no bathing on Thursday mornings for cleaning. The Hijiori way is to pair it with the morning market that sets up from about 5–6 am (Apr–Nov). In winter this is one of Japan's snowiest places, and just walking the street between snow walls is an experience. About 55 minutes by bus from Shinjō Station.
The communal bath at the heart of Nuruyu Onsen in Kuroishi, Aomori, a spa with more than 400 years of history. It is ringed by 'kyakusha' — simple self-catering cure lodgings with no baths of their own, whose guests all walk over here — a form of spa life now rare even in Tōhoku. The bathroom is as roomy as a sentō, with 100% source water (sodium chloride-sulphate) cooled by a special method without dilution and split into hot and lukewarm tubs. Adults pay ¥350; open long hours from 05:00 to 22:00 (last entry 21:30), daily (occasional closures in April and November). No soap provided. Kokeshi-doll workshops and the Tsugaru Kokeshi Museum are nearby. About 25 minutes by bus from Kuroishi Station.
A lone inn in a steaming fumarole field at about 1,000 m on the Akita side of Hachimantai. One of Tōhoku's great cure spas — 'arrive on horseback, leave on your own two feet', as the saying went — it is also famous for its ondol-heated cure wing. The main bathhouse lines up seven kinds of tubs: the signature box steam bath, a mud bath, a cascade bath, a 'volcano bath' and an open-air bath, all fed by milky acidic sulphur water. Day use 10:30–15:00 (last entry 14:00), ¥800 for adults, closed Tuesdays (plus maintenance days). Behind the inn a nature trail loops past mud volcanoes and vents in about 40 minutes. About 1 h 55 min by bus from Tazawako Station on the Hachimantai summit line (usually late Apr–mid-Oct); in winter come by local bus from Kazuno-Hanawa Station or by car.
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.
A mainly day-use hot-spring house at Senami Onsen in Murakami, Niigata, famous for sunsets over the Sea of Japan. Its own source 180 m down yields abundant water at about 94 °C, and although it is a seaside spa the water has a faint whiff of sulphur and leaves the skin silky. There is an indoor bath, a rugged rock-built outdoor bath and a mist sauna, and even the showers run spring water; in winter the outdoor bath becomes a snow-viewing bath. Private family baths, rentable rooms, weekday day plans with a meal (from ¥4,800) and overnight stays are also available. Adults ¥900, children ¥500, towel hire ¥210; open 09:00–22:00 (last entry 21:00), irregular closures. About 10 minutes by bus from JR Murakami Station or 12 minutes by car from Murakami-Senami-Onsen IC; 100 parking spaces. Combine with Murakami's salmon cuisine, its merchant townhouses and a sunset walk on Senami beach.
A municipal spa retreat in the mountains at the eastern edge of Ōno, Fukui, close to Lake Kuzuryū. Ringed by the clear Kuzuryū River and forested hills, it offers colourless, soft alkaline simple spring water in an indoor bath and an open-air bath overlooking the valley through fresh greenery, autumn colours and deep snow (the outdoor bath may close on winter weekdays). There are a sauna, a tatami rest hall and a restaurant, and the site forms part of the Kuzuryū Hoyō-no-Sato complex with cottages and the Hotel Flairal Izumi next door. Adults from outside the city pay ¥800 (residents ¥700), children from age 3 ¥400 (¥350). Open 10:00–21:00, from 12:00 on Wednesdays; closed Tuesdays (next day if a holiday) and 1 January. About 17 minutes on foot from Echizen-Shimoyama Station on the JR Etsumi-Hoku Line, or right off the Kuzuryū IC on the Chūbu-Jūkan Expressway. An easy stop after the Kuzuryū roadside station, an autumn drive around the lake or a climb of Mt. Arashima.
A town-run community centre at the gateway to Ōwani Onsen, a spa with 800 years of history south of Hirosaki. Just 2 minutes on foot from Ōwani-Onsen Station on the JR and Kōnan lines, its day bath Wani no Yu has an indoor pool, open-air bath, bubble bath and sauna. The clear sodium-calcium chloride and sulfate spring warms you to the core, and in winter the outdoor bath becomes a snow-viewing tub. Admission is a modest ¥550 for adults and ¥270 for children (town residents ¥400/¥200), and long hours of 9:00–22:00 are a strong point; two reservable family baths, Hagikatsura and Kawasemi, rent by the hour. Closed the third Thursday. Inside are a farm-produce corner, free rest areas with tables and tatami, and a lunch-only restaurant serving dishes and souvenirs made with the famous Ōwani onsen bean sprouts. Free parking for 80 cars. Open late enough to drop by after dinner in Hirosaki – a handy base for Hirosaki Castle or the Ōwani ski slopes.
A day bath inside Alpa Komakusa, the Semboku city complex where buses depart for the 8th station of Mt. Akita-Komagatake. Sharing the building with the mountain information centre and volcano disaster station, it bustles with hikers and Lake Tazawa sightseers. The 'Nature Onsen Hall' has two lookout open-air baths, one of rock and one of hiba cypress, gazing down on the lapis-blue surface of Lake Tazawa – Japan's deepest – and the sweep of the mountains. The milky simple sulfur spring rises from the same range as Nyūtō and Mizusawa onsen and warms a chilled body thoroughly with a soft sulfur scent. Admission is a modest ¥550 for adults and ¥300 for children. Hours are 9:00–19:00 (last entry 18:00) from April to November, 9:30–17:30 (last entry 17:00) from December to March, and 9:00–18:00 on Thursdays and Fridays; open daily except Thursdays from November to April. Rest corner and light meals available, with a large car park. From JR Tazawako Station take the Ugo Kōtsū bus bound for Nyūtō Onsen about 35 minutes to the Alpa Komakusa stop. Perfect for a soak on the way to or from Nyūtō or after climbing Komagatake.