Kusatsu Onsen was added to Your Favorites!
Joshin’etsukogen NP, Gunma
Claim this place to tell your story your way.
In 1726 and again in 1743, shogun Tokugawa Yoshimune had water drawn from Kusatsu’s Yubatake, sealed in barrels and sent to Edo Castle for bathing—a royal onsen delivery.
Kusatsu’s hot-spring-fed Yukawa was so acidic that downstream waters could not support fish. Since 1964, a nearby plant has continuously added powdered limestone—about 55 tonnes a day—to neutralize it.
Kusatsu’s highland flower beans grow in cool summer air at roughly 900–1,300 m. Families simmer these large beans with sugar and salt, serving them at festivals, celebrations and New Year.
The gourd-shaped Yubatake is a Taro Okamoto design, completed in 1975. The artist loved Kusatsu’s skiing and hot springs; he took a mayor’s request to turn a busy road into a place where people could pause.
Kusatsu residents once left on the 8th day of the 10th lunar month and returned on the 8th day of the 4th. This seasonal move to lower, less snowy Kuni villages, called fuyuzumi, lasted until about 1897.
In Kusatsu’s traditional timed bath, bathers stirred the water, poured about 30 ladles over their heads, then entered together for exactly 3 minutes at a leader’s calls—up to 4 rounds a day.
Kusatsu’s fame is on record by 1486, when the monk Gyōe stayed 14 days. In 1491, Zen monk Banri Shūku wrote of Kusatsu alongside Arima and Gero among Japan’s most revered hot springs.
German physician Erwin von Bälz helped put Kusatsu on the international spa map. After visiting from 1878, he studied its hot springs and praised the mountain air as well as the baths.
Yubatake is more than a scenic source: it releases about 4,040 liters of hot water a minute, and its water is piped to more than 80 inns and communal baths around Kusatsu.
The name Yubatake is younger than the spring: an 1884 map labels the site “Yu-batake.” Earlier records call the same place “Waterfall Base,” “Hot-Spring River” or “Hot-Spring Pond.”
Yu-no-hana means “hot-water flowers,” but the pale material is mineral sediment, not petals. Kusatsu gathers it from Yubatake’s channels several times a year, dries it for about a month and sells it as a bath additive.
Even Yubatake’s hot, acidic water has microscopic residents: a 2019 study cultured its microbes and isolated a previously unreported acid-loving bacterium.
Seven red-pine troughs, made from timber at least 150 years old, stretch about 40 m across Yubatake. They are not just decoration: the channels cool the flowing water without diluting it.
Kusatsu puts its hot-spring heat to work around town, using it to melt snow on roads and warm public buildings—so the volcanic resource keeps helping even when you’re not bathing.
Not every source is cooled with wooden paddles: Kusatsu’s Bandai spring emerges at about 94.5°C. A plate heat exchanger transfers its heat to water for the baths, bringing it to about 60°C.
The famous yumomi performance is younger than the technique: Netsunoyu began staging its paddle-and-song show in 1960, turning a practical way to cool hot water into a Kusatsu folk performance.
