To improve bath hot water useful for health and beauty by improving blood circulation inside the body by the negative ions of obsidian and far infrared rays.

By the development of ion balls of the obsidian produced in Wada pass in Nagano prefecture, generated negative ions are measured by using a prescribed apparatus, and 2,700 1CC negative ions are generated per ball (10 mm). The measured result of an ion generator for a household bath this time is 7,000 or more negative ions in 20 seconds. At present, an obsidian ion ball effect is considered to be incomparable. By the development, all the problems of a bath by disinfected water containing chlorine are solved, the effect similar to natural hot springs is obtained and the epoch-making development is easily used at home, in hotels and for a bedrock bath while requiring little maintenance and a small space. The device is also manufactured in a large size and used for a bedrock bath for business use and a sauna, etc., and is useful for welfare. The view of the bedrock bath by the name of our company (Yakuseki-no-yu) is publicized on the Internet.