A base for South Shinshu, a natural hot spring open 24 hours
Nagano Iida City
Tonooka Onsen Yumoto Yu-min in Iida, Nagano is a popular day-use and overnight facility that also serves as a convenient base for trips in South Shinshu. Day-use bathing is available until 24:00, and guests can enjoy silky alkaline natural hot spring water, a dry sauna, and a single-person cold plunge bath that is well chilled.
TypeNatural Hot Spring
A simple hot spring with a very high alkalinity of pH 10.3. The water is poured generously as a continuous flow from the source, and its slightly viscous, silky texture is characteristic, making it a skin-beautifying bath.
Sauna TypeDry Sauna
Stove Typeelectric
Capacity8people
Dry sauna equipped with a medium-sized convection stove at about 86–91°C. It is a quiet space without a TV where you can work up a good sweat.
Capacity1people
A round, single-person-sized cold plunge bath next to the sauna room. It has a perceived temperature of 15–18°C, providing a decidedly cold experience.
Closed Days: None
2F, 628 Kamitonooka, Iida, Nagano 395-0153, Japan
Gender Access
Gender Separated
Curated by an expert who visits onsen and sauna facilities every day and has explored 300+ locations — only facilities confirmed to be truly exceptional are featured.
Learn more
A base for South Shinshu, a natural hot spring open 24 hours
Nagano Iida City
Tonooka Onsen Yumoto Yu-min in Iida, Nagano is a popular day-use and overnight facility that also serves as a convenient base for trips in South Shinshu. Day-use bathing is available until 24:00, and guests can enjoy silky alkaline natural hot spring water, a dry sauna, and a single-person cold plunge bath that is well chilled.
TypeNatural Hot Spring
A simple hot spring with a very high alkalinity of pH 10.3. The water is poured generously as a continuous flow from the source, and its slightly viscous, silky texture is characteristic, making it a skin-beautifying bath.
Sauna TypeDry Sauna
Stove Typeelectric
Capacity8people
Dry sauna equipped with a medium-sized convection stove at about 86–91°C. It is a quiet space without a TV where you can work up a good sweat.
Capacity1people
A round, single-person-sized cold plunge bath next to the sauna room. It has a perceived temperature of 15–18°C, providing a decidedly cold experience.
Closed Days: None
2F, 628 Kamitonooka, Iida, Nagano 395-0153, Japan
Gender Access
Gender Separated
Curated by an expert who visits onsen and sauna facilities every day and has explored 300+ locations — only facilities confirmed to be truly exceptional are featured.
Learn more