Nishi-no-Kawara Rotenburo Kusatsu

Nishi-no-Kawara Rotenburo is Kusatsu Onsen's most dramatic outdoor bathing experience — a large open-air bath in a stone-paved garden setting surrounded by towering cryptomeria cedars in the heart of Japan's most celebrated traditional hot spring resort, where strongly acidic sulfurous waters at pH 2.0 flow naturally from the Yubatake hot spring field at the rate of 32,000 liters per minute. Kusatsu's waters are considered among Japan's most powerful for therapeutic efficacy, particularly for chronic skin diseases and metabolic conditions, and the ritual yumomi — ceremonially stirring and cooling the scalding spring water with wooden paddles — is performed daily as living cultural heritage. The elevated position of the Gunma highland spa at 1,200 meters ensures bracing mountain air, and winter snows transform the Yubatake central steam field into one of Japan's most photographed onsen spectacles.