Loaded with major ions — the essential minerals (Ca, Mg).
Buoyancy
Standard buoyancy
LowHigh
Soft water — natural, classic buoyancy.
BicarbonatesSodiumCalcium
Kusatsu is one of Japan's three greatest onsen resorts, producing the largest volume of hot spring water in Japan at 32,300 liters per minute, and its iconic Yubatake — the central wooden hot water field where steaming mineral water cascades through cooling channels — is the most recognized and photographed image in all of Japanese onsen culture. The Wakakusa Monogatari ryokan channels Kusatsu's characteristic strongly bicarbonate and acidic mineral water — cooled by the traditional yumomi paddle-stirring method — into refined baths in a setting that preserves the grand Gunma mountain onsen experience at its finest. Kusatsu's extraordinary mineral richness, its documented therapeutic tradition for skin, digestive, and circulatory conditions, and its position at the center of Japanese onsen culture make it the country's most scientifically esteemed and visitor-celebrated thermal resort destination.
Insider tip — Kusatsu is consistently ranked Japan's premier onsen town, famous for its Yubatake — a wooden-latticed hot spring field in the center of town where water cools from 95°C before channeling to the baths. The highly acidic water is celebrated for its germicidal properties and distinctive greenish-white color. The traditional yumomi ceremony, where attendants cool the water with long wooden paddles while singing folk songs, is a unique cultural ritual performed for visitors daily. Winter visits when snow blankets the Yubatake create an iconic image of Japanese spa culture.