小豆温泉 is a hot spring town in Fukushima, Japan. The water leaves the ground at 58–61°C, hot. Officially the water is classed as simple spring. 1 inns take visitors here.
Mild and low in dissolved minerals. Usually clear and gentle on the skin, which is why these baths are often recommended for first-timers.
Figures from the town's Japanese Wikipedia article.
37.0777, 139.4185 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.