A famous spring where the inn's own naturally gushing source, "Shionoha Onsen Nakamura Spring," which produces 500 liters per minute, is used as 100% free-flowing natural hot spring water with no added water. It has an extremely rich sodium-bicarbonate-chloride spring quality, and while the water is colorless and clear when it emerges, it gradually turns a beautiful golden color over time. The cedar-log public bath and the huge zelkova-log open-air bath have taken on a distinctive scaly appearance, almost like pottery or a limestone cave, as the hot spring minerals carried out by the water have hardened over many years. With the water kept just a little on the lukewarm side, you can enjoy soaking for as long as you like while gazing at the majestic gorge scenery of Ōsako Dam.