Located in a deep valley along the Hidaka River in Ryujin Village, Tanabe City, Wakayama Prefecture, Ryujin Onsen Motoyu is the only public bathhouse in the Ryujin Onsen area, which is renowned as one of Japan's Three Most Famous Beauty Hot Springs (Nihon San Bijin no Yu). The hot spring was discovered approximately 1,300 years ago by En no Gyoja, the founder of Shugendo mountain asceticism, and about 100 years later, Kobo Daishi (Kukai) is said to have established a bathing facility here after receiving a divine message from the Nanda Dragon King in a dream. The name Ryujin (Dragon God) derives from this legend. Motoyu features two different spring sources, both sodium bicarbonate springs. The bored spring used in the cypress bath has pH 8.4, a source temperature of 48.2 degrees Celsius, and flows freely from the source. The mixed natural spring from Kami-no-Yu and Shimo-no-Yu used in the main bath has pH 7.8, a source temperature of 43.3 degrees Celsius, and flows naturally with supplemental heating. The colorless and transparent water excels at removing old keratin and pore impurities, leaving skin remarkably smooth and moisturized, characteristic of its bicarbonate properties. The glass-walled main bath offers panoramic views of the valley, while the rustic outdoor bath surrounded by mountains provides a serene bathing experience with the sound of the Hidaka River. Operated by Tanabe City as a public facility, visitors can enjoy one of Japan's Three Beauty Springs for a reasonable admission fee of 800 yen. A self-catering annex for overnight stays is also available (closed in winter).