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.
Sister facility to Kin-no-Yu. Clear carbonated and radon water that leaves skin silky, plus a steam sauna. Usually less crowded than Kin-no-Yu. ¥700 on weekends/holidays, ¥550 on regular weekdays.
A five-minute ride down a 42-degree cable car to the bottom of the Iya gorge, where a self-flowing bath sits beside the river. Day use 7:30–17:00, cable car included. A member of the Secret Onsen Preservation Society.
The symbol of Nagayu, said to have Japan's most carbonated water. Sink into the 32°C open-air pool and silver bubbles coat your whole body. The charred-cedar and plaster building by architect Terunobu Fujimori is a sight in itself.
Arima's biggest day-spa complex: gold spring, silver spring and (artificial) carbonated baths — 26 baths plus stone saunas, with loungewear and towels included. Free shuttle from Arima-Onsen Station.
Eight minutes from Shimura-sakaue Station in Itabashi, one of Tokyo's most atmospheric super-sento, built around a Showa-era mansion and dry-landscape garden. Free-flowing olive-green spring water in the rotenburo, high-concentration carbonated bath, stone sauna and a soba restaurant. ¥970 weekdays, ¥1,300 weekends and holidays; open until midnight. No tattoos.
A day spa perched on a bluff with the whole Pacific in front of it — both the rotenburo and the sauna face the sea, giving sunrises in the morning and fishing-boat lights at night. Carbonated bath, stone sauna and restaurant; open 9 am to 1 am. ¥950 on weekdays. About 10 minutes by car from Hitachi-Taga Station on the JR Joban Line, doable as a day trip from Tokyo.
Kamata, 15 minutes by train from Haneda Airport, has Tokyo's densest cluster of 'kuroyu' black-water springs. Kaiseiyu, founded in 1929, is the classic: a coffee-dark natural bicarbonate bath, a high-concentration carbonated pool and a cold plunge, with a goldfish aquarium set into the bath wall. ¥600; a toiletries-and-towel set is sold at the desk. Ideal before a flight or after a late arrival. Tattoos are fine, as in most sento.
Eight minutes from Tsuruhashi Station, home of Osaka's Koreatown, a large bath complex known for its Japanese garden landscaping. Pot baths, a standing-depth bath, rock rotenburo and carbonated pool, plus a separately ticketed Korean-style 'hanjeungmak' stone-sauna zone. Open until 2 am — perfect after the yakiniku streets. Everything is charged to a wristband and settled on exit. ¥1,000 weekdays.
Hiroshima's largest natural-onsen complex, in Ujina near the port. Brown bicarbonate water in a rock rotenburo and free-flowing tubs, plus carbonated bath, sauna and stone sauna. Two-tier pricing: ¥500 for indoor baths only, ¥1,000 (weekdays) for everything. 25 minutes by tram from the Peace Memorial Park and close to the Hiroshima Port ferries for Miyajima.
Ten minutes by car from Kurobe-Unazuki-Onsen Station on the Hokuriku Shinkansen, a large day-spa wing of the lone inn Kintarō Onsen in Uozu. Its sulfur-rich sodium-calcium chloride water is among the most concentrated in Hokuriku, gushing at 1,800 litres a minute. A giant rock bath built from Tateyama boulders, open-air baths, a carbonated bath, rock-bath rooms and four private baths; open daily 8:30–23:30. Admission ¥1,100.
A super-sento 15 minutes by car from Kawagoe's 'Little Edo' warehouse streets, where brown natural spring water pumped from 1,200 m flows freely through both indoor and outdoor tubs. Nine baths per side plus two saunas, a carbonated bath and the signature 'Zabūn' water feature; the Zabūn and Sarasara wings swap between men and women on odd and even days. ¥900 weekdays, ¥1,000 weekends, ¥100 off 8–9 am and after 22:00. Open 8:00–25:00 every day with 200 parking spaces — a proper onsen near Tokyo to end a Kawagoe day.
Ise city's only full-scale super-sentō, attached to the Mitasu Ise shopping centre five minutes by car from the Outer Shrine. Funae Onsen water pumped from below fills the open-air stone and rock baths, joined by a high-concentration carbonated bath, jet baths and a tower sauna — eleven baths in all. Open 9:00–23:00 (last entry 22:30); ¥800 weekdays, ¥900 weekends and holidays, with towel-rental packages so you can drop in empty-handed between shrine visits. The Hyōtan-tei restaurant serves local dishes like Ise udon and tekone-zushi. About 20 minutes on foot from Iseshi Station, or right at the Mitasu Ise Kita bus stop (Mie Kōtsū).
A large super-sentō about 25 minutes from central Osaka on the Kita-Osaka Kyūkō line, ten minutes on foot from Minoh-Semba-Handai-mae Station (opened 2024). Certified therapeutic bicarbonate-chloride spring water feeds the open-air bath, joined by a high-concentration carbonated bath, pot tubs, lying baths and more — 17 tubs in all — plus a hot sauna with automatic löyly and an outdoor cool-down area. The stone-bed spa (extra ¥800) comes with some 6,000 manga and no time limit. Open 9:00–2:00 (from 6:00 on weekends and holidays; last entry 1:00); ¥1,000 weekdays, ¥1,100 weekends. Dining and relaxation services on site — an easy stop after hiking to Minoh Falls or visiting Expo '70 Park and EXPOCITY. Two maintenance closures a year.
One of the largest spa complexes in Saitama, in Kumagaya in the north of the prefecture. Its own alkaline simple spring, pumped from 1,500 m at over 600 litres a minute, feeds a wide range of tubs — a free-flowing open-air 'raw source' bath, pot baths, lie-down baths and a high-concentration carbonated bath. There is a löyly sauna, cold plunge and a garden-view outdoor rest deck. The optional 'Onkatsu Café Nest' adds eight kinds of bedrock-bath rooms, manga and free drinks for an all-day stay. Admission ¥950 on weekdays, ¥1,100 on weekends and holidays; open 10:00–23:00 (last entry 22:30), no closing days. Private rooms with an open-air pot bath can be reserved by phone. About 10 minutes by bus or taxi from JR Kumagaya Station; 300 free parking spaces. Kumagaya is about 40 minutes from central Tokyo by Shinkansen — combine with rugby at the stadium or Menuma Shōdenzan temple.
A natural hot spring to visit after strolling Kawagoe's 'Little Edo' warehouse street. Its own sodium-chloride spring from 1,200 m fills indoor and open-air baths in two zones, 'Wood' and 'Stone', which swap between men and women daily. Nine baths and three saunas in all — a carbonated bath made by dissolving CO₂ into the spring water, a free-flowing source bath, bedrock-bath rooms and a private family bath — make for an in-house bath-hopping course. Adults ¥850 on weekdays, ¥950 on weekends and holidays; open 10:00–24:00 (from 09:00 on weekends and holidays, last entry 23:00), no regular closing day apart from maintenance. Body soap and shampoo provided; a soba-and-udon restaurant, massage and body scrub are on site. Seibu bus from Hon-Kawagoe Station (Seibu Shinjuku Line) to the 'Hōmukyoku' stop; 150 free parking spaces.
The lone inn at Gokuraku Onsen, in the hills of Takaharu on the eastern foot of the Kirishima range, with water distinctive enough to be listed among Japan's 'hundred famous springs'. It is a carbonated iron spring (carbon dioxide-iron-calcium-bicarbonate), and the speciality is alternating between the free-flowing tubs, turned rust-red on contact with air, and a 'source cold bath' filled with the highly carbonated mineral water straight from the ground. Sitting in the cold fizzing water as tiny bubbles cling to your skin, then returning to the warm bath, is a routine sauna lovers adore. There is also an open-air bath, a sauna and a reservable private bath. Day bathing: adults ¥600, children ¥250, with long hours from 07:00 to 21:00 (last entry 20:30), except Wednesdays when it pauses 10:00–15:00 for cleaning. A dining room serves Kyushu mountain-and-river cuisine, and private rest rooms and overnight stays suit a cure-style visit. About 15 minutes by car from JR Takaharu Station or Takaharu IC. A hidden gem for Ebino Plateau and Kirishima trips.
A cure-bath founded in the Meiji era, tucked in the hills of Misato, Shimane, up a tributary of the Gō River. The spring bubbles up directly through gaps in the wooden floor of the tub — 'footspring' water that onsen devotees rank among the finest sources in western Japan. The carbonated iron-bicarbonate water is tepid at around 34 °C, faintly yellow-brown, and coats the body in tiny bubbles. There is one small wooden tub each for men and women, no washing area, soap and shampoo are forbidden, and bathing is limited to an hour: this is a place purely for soaking. Afterwards you can warm up in a heated goemon iron-kettle bath. Adults ¥500; open 08:00–18:00 April–October (last entry 17:00) and 08:00–17:00 November–March (last entry 16:00), closed Thursdays. Room rest is available. With the Sankō rail line gone, driving is realistic: about 1 hour from JR Gōtsu Station or 50 minutes from Ōasa IC on the Hamada Expressway, with a narrow mountain road at the end. Not for those wanting facilities, but unforgettable for those who care about the water itself.
One of the few natural-spring bath complexes on Okinawa's main island, on Route 58 in Ginowan next to the MEGA Don Quijote, about 30 minutes by car from Naha. The tea-brown water pumped from underground is a salty chloride spring that warms you well; besides the indoor bath, carbonated bath, sauna and cold plunge there is a pleasant garden open-air bath among tropical planting. Bedrock baths, private family baths, a recliner lounge and an inexpensive canteen round it out, and towels and shampoo are included so you can come empty-handed. Entry: adults ¥1,500, junior/senior high ¥1,000, children ¥750; open 07:00–23:00 (last entry 22:00), every day. Close to Chatan's American Village and the Ginowan beaches, it is handy on a rental-car trip or as a proper wash after a day in the sea — many divers stop by on the way home. 200 parking spaces.
A large day spa where you can gaze at Nagasaki's night view — ranked among the 'new three great night views of the world' — from the bath. Built on the slope of Mt Inasa, its rooftop open-air bath looks down over Nagasaki harbour and the city, which turns into a sea of lights after sunset. The alkaline simple water fills carbonated, electric and jet baths; there are several saunas and cold plunges, six family baths with rest rooms, a suite of bedrock baths (extra charge) and a self-service canteen. Adults ¥850 on weekdays, ¥900 on weekends and holidays, children ¥450; family baths from ¥3,000 for 60 minutes. Open late, 09:30–01:00 (until 02:00 on Fridays, Saturdays and holiday eves; last entry 30 minutes before), with no fixed closing days apart from maintenance. A free shuttle bus runs from JR Nagasaki Station (about 20 minutes), a big plus without a car. The classic plan pairs it with the Inasayama ropeway: see the view from the summit, then soak. 320 parking spaces; payment is mainly cash.
A day spa beside the 'Kamon Park Shinminato' roadside station in Imizu, on Toyama Bay. Its spring is a dense chloride water said to rank among the richest in Japan in dissolved minerals, with several times the free carbon dioxide of shop-bought bath fizzers, so onsen enthusiasts know it as a genuine carbonated chloride spring. The tea-brown, salty, iron-rich water warms you deeply; there are indoor and open-air baths, a sauna and a cold plunge. What stands out is the long day: an early-morning bath from 05:00 through to midnight (23:00 on Sundays), with cheaper early and late rates. Regular admission is ¥970 for adults (¥1,020 weekends and holidays), ¥750/¥780 early or late, ¥520 for children. Closed Mondays (open if a holiday, then closed the next weekday) and January 1. Easy to pair with the Shinminato Bridge, Kaiwo Maru Park and seafood at the Shinminato Kittokito market; about 10 minutes by car from Kosugi IC or 20 minutes by community bus from JR Kosugi Station.
A day-use hot spring in Jinsekikōgen, a plateau town at 500–700 m in eastern Hiroshima. The source, discovered in 1994 in the Iseki district of former Sanwa, is a rare pH 10.2 strongly alkaline, weakly radioactive cold mineral spring – low in irritants and gentle on the skin. The slightly cloudy, viscous water lifts excess oil and leaves skin smooth, which locals call a 'natural beauty serum'. Inside are an indoor bath, open-air bath, sauna and cold plunge, plus a rock-bed spa, carbonated tub and a private family bath, with a rest area and restaurant. Adults pay ¥900 and children of elementary age or under ¥500; coupon books and a monthly pass keep the regulars coming. Open 10:00–21:00, closed Tuesdays, parking for 20 cars. About an hour by car from central Fukuyama via Route 182, or 2 minutes on foot from the Iseki-naka bus stop. Pair it with Taishaku Gorge, Jinseki beef and stargazing on a drive across the highlands.
A lone hot spring inn at Kamuta in Takaharu, Miyazaki, on the eastern foot of the Kirishima range. A therapeutic bathing spot since the Meiji era, its pride is an extremely carbonated spring with 1,314 mg/kg of free carbon dioxide. Ease into the unheated, chilly carbonated pool and fine bubbles cling to every inch of skin – a concentration said to equal 10–25 bath-fizz tablets. The heated indoor and open-air baths glow golden with iron-rich cloudy water, and alternating between them and the cold spring is the house ritual; a drinking fountain lets you taste the sharply fizzy, iron-flavoured source too. Day bathing costs ¥650 for adults and ¥300 for ages 3–12, 10:00–21:00 (last entry 20:30), closed as a rule on the first and third Wednesdays (subject to change). Day-rest rooms, tatami rooms and detached cottages for overnight stays, and meals of local produce are available. About 10 minutes by car from Takaharu IC on the Miyazaki Expressway, with parking for about 60 cars. Combine it with Kirishima Shrine, a climb of Takachiho-no-mine or the Ebino plateau.
A lone day-bath building among the fields on the outskirts of Nirasaki, north-west of the Kōfu basin, and a nationally known pilgrimage spot for onsen lovers. Nothing is added or altered – no dilution, heating, recirculation or chlorine – and as you settle into the tepid 38°C sodium chloride-bicarbonate spring, your whole body is coated in fine bubbles, said to be among the most abundant in Japan. The faintly greenish-yellow water carries a whisper of sulfur and iron, and the source running from a tap in the bathroom can be drunk (fizzy, iron-tinged). There is no open-air bath or sauna – just one big indoor pool and washing stations, like a sentō – but the windows frame the Yatsugatake and Kayagatake peaks, and the mild water makes an hour disappear. Adults pay ¥600, children ¥300, soap and shampoo provided. Open 10:00–20:00, closed Tuesdays (next day if a holiday) and Fridays, with free parking for 25 cars. About 10 minutes by taxi from Nirasaki Station on the JR Chūō Line or 15 minutes from Nirasaki IC on the Chūō Expressway.
A big natural hot spring super-sentō 3 minutes on foot from Suminoekōen Station on the Osaka Metro Yotsubashi Line, right beside the Suminoe boat-race stadium. Its pride is a sprawling open-air zone fed by sodium-chloride spring water: a bamboo path, garden-style rock bath, pot tubs and a lie-down 'forest pot bath' that feel far from the city. Indoors are jet baths, an electric bath, the popular high-concentration carbonated pool, a salt sauna, hot sauna and cold plunge. Prices are modest – adults ¥800 on weekdays and ¥900 on weekends and holidays, children ¥400/¥450 – with a hand stamp for same-day re-entry. Open 10:00 to 2:00 am (last entry 1:00), all year except maintenance days. An udon-centred restaurant and rest areas are attached, and free parking for about 850 cars (3 hours with bathing, 6 with a meal). About 15 minutes by subway from Namba, it is a bayside hideaway you can drop into late after USJ or the Nankō waterfront.