Kusatsu Onsen

Eight centuries of medicinal bathing

Kusatsu's discovery is wrapped in legend: the chronicles credit Yamato Takeru, later the Nara-period monk Gyōki, and by the late twelfth century Minamoto no Yoritomo is recorded as having bathed here. By the Edo period the village was a working spa town with a formal ranking system among bathers, and Kusatsu had entered the national imagination as a place people went to be cured.

The town turned medical in the late nineteenth century. The German physician Erwin von Bälz, court doctor to the Meiji emperor, studied the springs in the 1880s and recommended the resort to Western medicine, which helped fix Kusatsu in the lineage of European-style Kurort towns. Around the same time the jikan-yu method (short, supervised bathing sessions in undiluted hot water) was codified at the bathhouses around the source, and the yumomi cooling ritual took the form it still has today.

The Yubatake and the smell of sulfur

The town is built around the Yubatake (湯畑, "hot water field"), a sunken wooden cascade in the center of the village where roughly 4,000 liters of spring water rise every minute, cool across seven channels, and collect the pale-yellow yu-no-hana mineral flowers harvested since the Edo period. The current layout, including the gourd-shaped stone basin and the surrounding promenade, was redesigned in 1975 by the artist Okamoto Tarō. Steam drifts continuously through the streets; the smell of sulfur is the first thing visitors notice and the last thing that leaves their clothes.

Because the source water reaches the village at 50–90°C, it has to be cooled before anyone can enter it, and adding cold water would dilute the minerals. The solution is yumomi, performed daily at Netsu-no-yu beside the Yubatake: rows of women in indigo happi coats stir the bath with 1.8-meter cedar paddles, singing the Kusatsu-bushi folk song to keep time. It is half cooling method, half folk theatre.

Beyond the central baths

A ten-minute walk downhill leads to Sainokawara Park, where hot water flows openly through a forested ravine and feeds one of Japan's largest outdoor baths. The town also keeps a small network of free neighborhood bathhouses (kyōdō-yu) reserved primarily for residents but with three open to visitors, each fed by its own named source. Winters here are cold and snow-locked; Kusatsu doubles as a ski resort from December through March, which makes the contrast between the snow and the steam its own argument for visiting off-season.