Ramune Onsenkan is a unique wooden building designed by architect Terunobu Fujimori. Pine trees, which are a symbol of celebration, are planted on the triangular roof, creating a playful space.

Ramune Onsenkan has two baths, an open-air bath and an indoor bath. The open-air bath is a “ramune hot spring” where the whole body is wrapped in silver bubbles. The temperature of Ramune Onsen is as low as 32 degrees Celsius, but the stimulation of carbon dioxide can be expected to promote blood circulation and beautify the skin. The indoor bath is a 42-degree "cloudy water" that can be expected to help you recover from fatigue and keep you warm.