At the large bath Yuzan no Yu, the right-hand tub draws the gentle Nishinokawara Spring, while the left-hand tub draws the strongly acidic and powerful Bandai-ko Spring. This is an exceptionally luxurious bath where you can compare two of Kusatsu's signature springs at once. In the high-ceilinged, boldly timbered space, you can fully experience the differences in texture, cleansing effect, and warmth retention of each spring with your whole body.

The large bath Bandai no Yu lets you enjoy 100% free-flowing water from Bandai-ko Spring, the spring with the highest output in Kusatsu Onsen and a powerful source that naturally gushes at high temperature. Highly acidic, it is known for its extremely strong antibacterial and anti-inflammatory effects, warming the body from the core. After enjoying this famous spring in the indoor bath, you can indulge in a luxurious nature bath in the atmospheric open-air bath that blends into a beautifully maintained Japanese garden.

The large bath Nishi no Yu uses the extremely precious Nishinokawara Spring, which only about six inns in Kusatsu draw, with free-flowing spring water. Among Kusatsu's more stimulating waters, it is exceptionally gentle and characterized by a very soft feel on the skin. It has a spacious indoor bath and a half-open-air bath styled like a Japanese garden, with stone paving and trees, where the smooth, mellow water gently leaves your skin moist and cared for.

A luxurious private free-flowing hot spring bath available in some of Boun's guest rooms. With in-room indoor hot spring baths in the new main building and open-air baths in Unshoan, guests can enjoy Kusatsu's famous waters whenever they like, in an exquisite space where no one will disturb them. It is a truly exceptional luxury to have all of Kusatsu's powerful, original hot spring energy to yourself during your stay, distinct from weakly alkaline waters.