Gaga Onsen is a secluded single-inn hot spring located at approximately 850 meters elevation along the Nigori River on the southern slopes of the Zao Mountain Range in Kawasaki Town, Shibata District, Miyagi Prefecture. The spring was discovered during the Kaei era (1848-1853) when a hunter named Rokuji found an injured deer bathing in the waters, earning it the name 'Deer's Bath.' An inn was established in 1876 (Meiji 9), and it has continued its tradition as a therapeutic bathing retreat for approximately 150 years. The spring water is a sodium-calcium bicarbonate-sulfate spring with pH 6.6, a source temperature of 58 degrees Celsius, and flows at 100 liters per minute as 100% free-flowing natural spring water. It is renowned as one of Japan's Three Great Gastrointestinal Healing Hot Springs, alongside Shima Onsen in Gunma and Yunohira Onsen in Oita. The inn preserves the traditional three-method cure: pouring water over the body (kakeyu), drinking the spring water (insui), and bathing (nyuyoku). The unique kakeyu method involves using a bamboo ladle to pour warm water over the stomach area approximately 100 times. The facility features 10 bathing pools including a main bath with hot (47 degrees) and warm (38-42 degrees) pools, gender-separated outdoor baths, a mixed outdoor bath (closed in winter), and a private outdoor bath called Tenku no Yu. Guest rooms are single-story wooden structures built with cedar and cypress, all equipped with floor heating. The cuisine emphasizes digestive-friendly dishes using local Zao and Sanriku ingredients. Banquets and karaoke are prohibited to maintain a peaceful therapeutic environment. Four-wheel drive vehicles or tire chains are required during winter.