Public bathhouse · Open
Shirahata-no-yu
- Day-use bathing
- Yes
- Fee
- ¥0checked 2026-10-09
- Hours
- 8:00–23:00checked 2026-10-09
Photo information
Save to passport
Official classification
Spring type (therapeutic classes)
Official spring-type name (as recorded)Acidic, sulfur-bearing aluminium sulfate–chloride hot spring (formal name for the Yubatake and similar sources; varies by source)
- Source temperature
- 44.9–94.5°C
- pH
- 1–2.2
- Flow rate
- 32,300 L/min
- Radon
- Unconfirmed
Appearance & feel
Water colour · Feel
ClearMilky whiteYunohana (mineral flakes) · Yes
Colour and feel are listed only where a source states them. They vary by day and by bath.
What makes it special
Thirty-two thousand litres a minute of pH 2.1 acid water rise in the middle of town and cool as they run down wooden channels.
Why?
The Kusatsu Onsen Tourism Association states a natural flow of over 32,300 litres a minute, the largest in Japan, a pH of 2.1 at the Yubatake source, and about 4,000 litres a minute from the Yubatake itself.[2]
Facilities in this area
Facilities come from the register (Wikipedia, OpenStreetMap, official sites). Those marked "natural spring unconfirmed" are listed on the basis of their name only.
Public bathhouse · Open
Jizo-no-yu
- Day-use bathing
- Yes
- Fee
- ¥0checked 2026-10-09
- Hours
- 8:00–22:00checked 2026-10-09
Day-use bath · Open
Otaki-no-yu
- Day-use bathing
- Yes
- Fee
- ¥1,200checked 2026-10-09
- Hours
- 9:00–21:00checked 2026-10-09
Day-use bath · Open
Goza-no-yu
- Day-use bathing
- Yes
- Fee
- ¥900checked 2026-10-09
- Hours
- 4–11月 7:00–21:00 / 12–3月 8:00–21:00checked 2026-10-09
Baths2
| Type | Gender | Source | Bath temperature | Free-flowing | Added water | Heated | Recirculated | Disinfected |
|---|---|---|---|---|---|---|---|---|
| Indoor bath | Separate | Yubatake and Bandaiko | Unconfirmed | Unconfirmed[9] | Unconfirmed[9] | Unconfirmed[9] | Unconfirmed[9] | Unconfirmed[9] |
| Indoor bath | Separate | Yubatake and Bandaiko | Unconfirmed | Unconfirmed[9] | Unconfirmed[9] | Unconfirmed[9] | Unconfirmed[9] | Unconfirmed[9] |
Day-use bath · Open
Sainokawara open-air bath
- Day-use bathing
- Yes
- Fee
- ¥800checked 2026-10-09
- Hours
- 4–11月 7:00–20:00 / 12–3月 9:00–20:00checked 2026-10-09
Getting there
Reachable by public transport
From Ueno take the JR limited express 'Kusatsu-Shima' about 2 h 33 min to Naganohara-Kusatsuguchi, then a JR Bus Kanto bus about 25 minutes to Kusatsu Onsen bus terminal. From Karuizawa, Kusakaru Kotsu or Seibu buses take 1 h 18 min to 1 h 55 min. The 'Joshu Yumeguri' express bus runs from Tokyo Station and Busta Shinjuku.
- Getting there
- Naganohara-Kusatsuguchi Station · 25
- Through the year
- At about 1,200 m; winter tyres or chains are required. The Shiga-Kusatsu road (Route 292) closes in the snow season.
- Checked
- 2026-10-09
About the water
Kusatsu's water is strongly acidic, pH 2.1 at the Yubatake source, about as sour as lemon juice, and the tourist association points to its strong germ-killing power. There are several sources (Yubatake, Shirahata, Sainokawara, Jizo, Nikawa, Bandaiko and more) and they look different, from clear to milky; Jizo-no-yu is 'slightly cloudy', and Otaki-no-yu declares the second and fourth Saturdays 'cloudy-water days'. Source temperatures run from the 50s to over 90 °C, far too hot to enter, hence the Yubatake's cooling channels and the yumomi boards. Yunohana flakes are a by-product of that cooling. Otaki-no-yu's notice lists indications such as neuralgia, joint pain and chronic skin conditions; we make no medical claims.
Indications (as posted on the analysis)
Posted at Otaki-no-yu: neuralgia, joint pain, bruises, sprains, burns, chronic digestive complaints, convalescence, chronic gynaecological complaints and others
Indications are an official statement based on the water analysis, not a guarantee of treatment. They are kept separate from opinions.
| Source | Source temperature | pH | Radon | Checked |
|---|---|---|---|---|
| Yubatake | Unconfirmed | 2.1 | Unconfirmed | no check date |
| Nikawa (Otaki-no-yu) | Unconfirmed | 2.1 | Unconfirmed | no check date |
| Shirahata | Unconfirmed | Unconfirmed | Unconfirmed | no check date |
| Jizo | Unconfirmed | Unconfirmed | Unconfirmed | no check date |
| Bandaiko | Unconfirmed | Unconfirmed | Unconfirmed | no check date |
Three things not to miss
Photo information
Yubatake
Centre of town A source giving about 4,000 litres a minute is run down wooden channels to cool it and to collect yunohana mineral flakes. Around it are boardwalks and a plaza with benches shaped like Mt Shirane.
The clearest possible demonstration that Kusatsu's water is too hot to bathe in as it comes. Lit at night, it is the town's living room and its clock.[2][1]
Yumomi and jikan-yu at Netsu-no-yu
Beside the Yubatake A show in which bathers cool the water by beating it with long boards, sung to folk songs: 700 yen, six or more sittings a day (9:30, 10:00, 10:30, 15:30, 16:00, 16:30 and extras). From 11:30 to 12:50 you can try it yourself for 300 yen.
A technique invented to cool scalding water without diluting it. With jikan-yu, three-minute immersions on a bath-master's command, it is a bathing culture unique to Kusatsu.[4]
Photo information
Free public baths: Shirahata, Jizo and Chiyo
1–3 minutes from the Yubatake Neighbourhood baths opened free to visitors: Shirahata-no-yu 8:00–23:00, Jizo-no-yu 8:00–22:00, Chiyo-no-yu 6:00–23:00. No lockers, and they close for cleaning in the mornings.
Each uses a different source (Yubatake, Shirahata, Jizo), so you can compare the town's waters side by side. Treat them as the locals' baths you have been lent, and keep quiet.[5][6][7]
The story
Japan's biggest flow
Kusatsu sits at about 1,200 m on the eastern flank of Mt Shirane. The tourist association puts its natural flow at over 32,300 litres a minute, the largest in Japan, roughly 230,000 oil drums a day. The Yubatake in the centre of town alone gives about 4,000 litres a minute. There are several sources, Yubatake, Shirahata, Sainokawara, Jizo, Nikawa, Bandaiko among them, all strongly acidic; the Yubatake source is pH 2.1. It has long been counted with Arima and Gero as one of Japan's 'three great springs'.[2][11]
Never dilute the water
Kusatsu's sources are over 50 °C, far too hot to enter. Adding cold water would be easy, but it would weaken the water. Instead the town devised the Yubatake's wooden channels, which cool the water as it flows, and yumomi, beating and stirring the bath with long boards. Yumomi went hand in hand with jikan-yu, a regime in which everyone enters together on the bath-master's signal for about three minutes. At Netsu-no-yu the yumomi is performed as a show with folk songs, and at midday visitors can try it.[4][2]
Borrowing the town's baths
Kusatsu has many neighbourhood baths, and three of them, Shirahata-no-yu, Jizo-no-yu and Chiyo-no-yu, are open to visitors free of charge, all a few minutes from the Yubatake. There are no lockers, they close for cleaning in the morning, and no soap is provided. Each draws on a different source, so you can compare Shirahata (milky), Jizo (slightly cloudy) and Chiyo (Yubatake water). These are the locals' daily baths: be quiet and be brief.[5][6][7]
The three day-spas
For visitors there are three day-use bathhouses known as the 'Kusatsu Santo'. Goza-no-yu (900 yen), facing the Yubatake, is a wooden recreation of an Edo–Meiji bathhouse fed by both the Yubatake and Bandaiko sources. Otaki-no-yu (1,200 yen) uses the Nikawa source and is known for awase-yu, a series of tubs at rising temperatures. The Sainokawara open-air bath (800 yen), about 500 m² across both sides, sits at the top of Sainokawara Park.[8][9][10]
Going solo
Easy for solo travellersUnconfirmed
Weekend / peak restrictionsUnconfirmed
Where to eat dinnerMany restaurants around the Yubatake
Private bathYes
checked 2026-10-09
Through the year
Recommended months
JanFebMarAprMayJunJulAugSepOctNovDec
Months open
JanFebMarAprMayJunJulAugSepOctNovDec
"Recommended" and "open" are recorded separately. Check the season for seasonal springs.
Aug — Kusatsu Onsen Thanksgiving Festival, 1–2 August (Wikipedia)
Dec · Jan · Feb · Mar — Snow bathing (Sainokawara opens at 9:00 in winter); ski area open. Roads ice over, so the bus is the safer choice
May · Jun — The Shiga-Kusatsu road reopens, opening the route over toward Mt Shirane
Food, culture & experiences
Yumomi and dance show (Netsu-no-yu)
700 yen adults, 350 yen children; try yumomi yourself 11:30–12:50 for 300 yen[4]
1 minute from the YubatakeSainokawara Park
A park where hot water seeps from the stony riverbed and runs as a warm stream; the big open-air bath is at the top[10]
About 10 minutes' walk from the YubatakeOnsen eggs and foot baths
Eggs cooked in the spring water are sold around the Yubatake; free foot baths at the bus terminal and by Jizo-no-yu[12]
Around the YubatakeKusatsu ski area and Mt Shirane
Skiing in winter; in summer the road toward Mt Shirane, subject to volcanic-activity restrictions[1][11]
10–30 minutes by car or busEditors' guide
Day one: walk round the Yubatake, watch the yumomi at Netsu-no-yu, then bathe in Yubatake-source water at Goza-no-yu or the free Shirahata-no-yu. Day two: walk up through Sainokawara Park to the open-air bath, and finish with Otaki-no-yu's stepped tubs. The free baths have no soap or lockers; keep soaks short. In winter, come by bus.
The "editors' guide" above is written by the editors from sources; it is not a visitor's opinion.
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Overview
Kusatsu Onsen (草津温泉) is a hot spring resort located in Gunma Prefecture, Japan, northwest of Tokyo. It is a popular tourist destination. There are 13 public baths at Kusatsu Onsen. The small bathhouses that are free for both town residents and tourists are managed by the townspeople themselves. The source of its hot water is nearby Mount Kusatsu-Shirane and the appearance of the waters range from cloudy to clear, because the sources of the water that the baths rely upon are different. The springs were known as a resort for centuries, but they became well known after the water was recommended for its health benefits by Erwin von Bälz, a German doctor who taught medicine at Tokyo University. The locals claim the hot springs can cure all forms of ailments, other than lovesickness. Guests have claimed that pain disappears while soaking in its hot water.
This overview is based on the lead section of the English Wikipedia article (CC BY-SA 4.0). View original page
Onsen areas nearby
Unconfirmed & notes
- Source temperatures and analysis sheets could not be read on official sites (Wikipedia gives 44.9–94.5 °C)
- Otaki-no-yu's individual tub temperatures, added-water notices at Goza-no-yu and Sainokawara, and tattoo policies unconfirmed
- JR bus fare/frequency and express-bus times/fares not confirmed officially
- Chiyo-no-yu is officially free, 6:00–23:00; conditions for jikan-yu sessions unconfirmed
Sources
- 草津温泉観光協会 公式サイト(草津温泉ポータル)草津温泉観光協会 · 2026-10-09
- 草津温泉観光協会 温泉について草津温泉観光協会 · 2026-10-09
- 草津温泉 アクセス(電車・バス)草津温泉観光協会 · 2026-10-09
- 熱乃湯 湯もみと踊りショー草津温泉観光協会 · 2026-10-09
- 白旗の湯草津温泉観光協会 · 2026-10-09
- 地蔵の湯草津温泉観光協会 · 2026-10-09
- 千代の湯草津温泉観光協会 · 2026-10-09
- 大滝乃湯 公式サイト(ご利用案内・温泉)草津温泉 大滝乃湯 · 2026-10-09
- 御座之湯 公式サイト(ご利用案内)草津温泉 御座之湯 · 2026-10-09
- 西の河原露天風呂 公式サイト(ご利用案内)草津温泉 西の河原露天風呂 · 2026-10-09
- 草津温泉 - WikipediaWikipedia · 2026-10-09
- 草津温泉観光協会 温泉・入浴施設一覧草津温泉観光協会 · 2026-10-09
Register sources
- 草津温泉 - Wikipedia(日本語版)Wikipedia · CC BY-SA 4.0 · 2026-10-09
- Wikidata Q3137477Wikidata · CC0 · 2026-10-09
Data status
Name & locationPublishedCoordinatesPublishedSpring typePublishedPhotosPublishedFacilitiesPublishedVisiting info (dated)PublishedEditorial articlePublished
Updated 2026-10-09
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