Bokoro is a historic hot spring inn founded in 1931 (Showa 6) on the western shore of Lake Togo, a brackish lake in Yurihama Town, Tottori Prefecture. It is widely known for its unique 'lakeside open-air bath' built out over the surface of Lake Togo, accessed by crossing a red wooden footbridge and offering uninterrupted panoramic views of the lake, the surrounding mountains, and the sky. Hawai Onsen itself was discovered in 1843 (Tenpo 14) when local fishermen found hot water naturally welling up from the bottom of Lake Togo, making it one of the most distinctive lake-bottom onsen origins in Japan. The water quality is a sodium-calcium chloride and sulfate spring (hypotonic, weakly alkaline, high temperature), and every bath at Bokoro uses 100% free-flowing source water with no added water, no reheating, and no recirculation filtration. Facilities include the prefecture's largest-class indoor bath 'Tennyo no Yu', the semi-open-air 'Shinwa no Yu', the lakeside open-air bath, private baths, and a foot bath. The entire facility was fully renovated in April 2019.