Iide Onsen Kawairiso

Kawairiso is a day-use hot spring bathhouse in Kotamagawa, Oguni Town, Yamagata Prefecture, set in the Tamagawa valley on the approach to the Iide mountain range. It stands next to the public lodge Iide Kairagiso as its annex, and is known for a log-cabin viewing bath looking straight out at the Iide peaks. Iide Onsen is said to have some eight centuries of history, and its water now serves three facilities: Kairagiso, Kawairiso and Iide Sanso.

The water is classified as a sodium-calcium chloride, bicarbonate and sulfate spring, hypotonic, neutral and hot, with a pH of around 6.6. It is piped in from a blend of source wells numbered one through five. The bath is a clear yellow-tinged colour, and rust-red mineral deposits from its iron content cling to the rim of the tub. According to the notice posted at the facility, the water is diluted, reheated and supplied through a combined overflow-and-circulation system. It is traditionally said to help with digestive complaints, injury after-effects, rheumatism, gout and chronic gynaecological conditions.

Bathing is limited to the single open-air viewing bath; there is no indoor tub and no washing area with taps. The facility currently operates for day-use bathing only and does not accept overnight stays or room rest plans. Admission is 500 yen for adults, including 50 yen bathing tax, and 300 yen for elementary school children, which also covers the panoramic indoor bath at neighbouring Kairagiso. Reception is at the Kairagiso front desk, hours are 10:00 to 18:00 with last entry at 17:30, and the bath is closed on Tuesdays and throughout the winter season from early November to late April.