Located along the upper reaches of the Hidaka River in Ryujin Village, Tanabe City, Wakayama Prefecture, Ryujin Onsen is one of Japan's Three Great Beauty Hot Springs, renowned nationwide for its skin-beautifying waters. The hot spring was discovered approximately 1,300 years ago by the ascetic En no Ozunu, and it is said that Kobo Daishi (Kukai) later established a bathing facility here following a divine message from the dragon king Nanda. Shimogoten was founded in 1639 when Tokugawa Yorinobu, the first lord of the Kishu Tokugawa domain, designated Ryujin Onsen as the domain's official hot spring, and it prospered as the lord's exclusive bathing retreat. The water is a sodium bicarbonate spring with pH 7.8, mildly alkaline, with source temperatures of 43.6 to 46.0 degrees Celsius. The colorless and transparent water is famous for making skin silky smooth. Shimogoten's most distinctive feature is its nationally rare Ozashiki-buro (tatami bath), where the entire area from the changing room to the bathtub is covered in tatami mats, creating a unique bathing experience. All guest rooms face the Hidaka River, offering a serene environment with the sound of the flowing stream and views of lush green mountains. As a member of the Japan Association of Secluded Hot Spring Inns, Shimogoten is beloved by hot spring enthusiasts for its rich history and elegant atmosphere.