What Is Kusatsu Onsen? The Yubatake and the Strongly Acidic Water
This guide is for visitors who want to know what makes Kusatsu Onsen different from other hot spring towns in Japan. It covers the Yubatake, the strongly acidic spring water, the town's old bathing culture and the public baths run by the town.
We used pages from the Kusatsu town office, all read on 2026-10-04. Opening hours and prices change, so check the current information before you go.
The short answer: a town built on very acidic water
The town office says all of Kusatsu's springs flow out by themselves. Its main water type is described as "acidic, hypotonic, high-temperature". The pH is around 2.0.
The town makes the strength of the water easy to picture. It says that if you leave a five-sun nail in the Yukawa stream, it dissolves in about ten days. A "sun" is an old unit of about three centimetres, so the nail is about 15 centimetres long.
What is the Yubatake?
The Yubatake is the symbol of Kusatsu Onsen. The town office says it sends out 4,000 litres of hot spring water every minute.
It lies in the middle of the hot spring town. Souvenir shops and restaurants stand around it, and the town says it is always crowded. At night it is lit up, and the light and the steam together look mysterious. The town recommends the twilight hour after sunset.
The Yubatake was chosen as one of the "100 Fragrance Landscapes" in 2002. In 2017 it was designated a national Place of Scenic Beauty.
Where does the water come from?
The town says there are dozens of spring sources. Most are owned or managed by the town. Six are named as the main ones: Bandai, Yubatake, Shirahata, Jizo, Nishi-no-Kawara and Nikawa.
The sources differ a little in water quality. The Bandai source is hot, about 94.5°C. The town cools it to about 60°C by passing it through a heat exchanger with tap water before it goes to the baths. The other sources come out at about 50°C and have been used as they are since old times.
The town also uses the spring heat to melt snow on roads and to warm public buildings.
A long history of bathing
The town office lists three legends about the opening of the springs. They name Yamato Takeru, the monk Gyoki and the warlord Minamoto no Yoritomo.
It says many warlords came to bathe for their health in the warring-states period. In the late Edo period, more than 10,000 bathers a year came, including writers and poets. The town was praised in a saying that Kusatsu had a thousand houses built in the style of Edo. The town also says the eighth shogun, Yoshimune, had the water carried to Edo Castle to bathe.
Public baths run by the town
The town says it has 19 shared baths. Some are free, and the town says visitors can use them as well as residents. Its page on the shared baths sends readers to the Kusatsu Onsen Tourism Association site for details, so we did not read the rules ourselves.
The town also runs bathing facilities near the Yubatake. These are the three on its own list:
- Gozanoyu. The town says it rebuilds one of five old shared baths that stood near the Yubatake in the Edo and Meiji periods. One story links the name to a stone where Minamoto no Yoritomo sat.
- Otakinoyu. It has large baths, a sauna and an open-air bath with a big water curtain. The town gives the hours as 9:00 to 21:00, with the last entry at 20:00. It gives the price as 1,200 yen for adults and 600 yen for children aged three to elementary school.
- Nishi-no-Kawara open-air bath. The town calls it one of Japan's leading open-air baths. It says Friday is a mixed-bathing day. The hours are 7:00 to 20:00 from 1 April to 30 November, and 9:00 to 20:00 from 1 December to 31 March. The last entry is 19:30. The price is 800 yen for adults and 400 yen for children.
The town sells a set ticket for these three baths. It says the usual total is 2,700 yen for an adult, and the set costs 1,950 yen. For children it is 900 yen instead of 1,350 yen. The ticket has no expiry date.
There is also a "face bath" in the Ura-Kusatsu Jizo area. The town says it lets you breathe in the mist of the Jizo spring on your face, and that this is rare in Japan.
Nishi-no-Kawara Park
This park lies west of the hot spring town. The town says hot water rises almost everywhere, sending up clouds of steam and flowing away as the Yukawa stream.
Because of this view, people once feared it as a place where demons live. A tradition says you must not shout there. Names such as the "demon's teakettle" and the "demon's sumo ring" remain. The park has poem monuments, including one for Dr. Baelz, who helped spread Kusatsu's fame abroad. It is lit at night.
Yu-no-hana, the mineral deposit
The town sells "yu-no-hana", the mineral deposit from the springs. A pack of 95 grams costs 1,400 yen, according to the town. It is sold at souvenir shops and inns in town. The town asks buyers to read the cautions on the pack before use.
What we could not verify, and therefore left out
- The rules of the shared baths, and which ones are free to visitors today. The town's page points to the tourism association's site, which we did not read for this.
- Any health effects. The town describes the water as "excellent for healing", but we did not look for medical sources.
- Whether the strongly acidic water suits every skin type, or any age or health limits for bathing.
- Show schedules such as the yumomi hot water show.
Related guides
- How do you get to Kusatsu Onsen from Tokyo?
- How do you stay safe in Kusatsu? The volcano, volcanic gas and bears
Sources
All URLs retrieved 2026-10-04.
- 草津温泉について (Kusatsu Town) — (acidic water, pH, six main sources, temperatures, history, 19 shared baths)
- 湯畑 (Kusatsu Town) — (4,000 litres a minute; lit at night; 2002 and 2017 designations)
- 御座之湯 (Kusatsu Town) — (rebuilt old shared bath; name story)
- 大滝乃湯 (Kusatsu Town) — (facilities, hours, prices)
- 西の河原露天風呂 (Kusatsu Town) — (hours, prices, Friday mixed bathing)
- 「ちょいな三湯めぐり手形」をご利用ください (Kusatsu Town) — (three-bath set ticket and prices)
- 西の河原公園 (Kusatsu Town) — (steam, demon tradition, monuments)
- 湯の花について (Kusatsu Town) — (pack size and price; where sold)
- 顔湯 (Kusatsu Town) — (spring mist for the face)
- 「共同浴場」をご利用される皆様へ！ (Kusatsu Town) — (shared-bath information is on the tourism association site)