The sixth of nine public bathhouses in Shibu Onsen, Yamanouchi Town, Nagano Prefecture. As its name suggests, there is a legend that people have washed their eyes with this water to cure eye diseases since ancient times. The source names are 'Mearai no Yu' and 'Ganizawa no Yu', with water quality of sodium-calcium sulfate-chloride hot spring (hypotonic, neutral, high temperature). The source temperature is 50.6°C, making it relatively easy to enter among the nine baths. With a pH of 7.6 (neutral to weakly alkaline) and the lightest mineral content among the nine baths, it places the least burden on the body. Besides its effectiveness for eye diseases, it is also called the 'Beauty Bath' for its skin-beautifying effects and is popular among women. It is also said to be effective for neuralgia, muscle pain, chronic gynecological conditions, and arteriosclerosis. Shibu Onsen has a history of approximately 1,300 years with 37 hot spring sources.