Kojigoku Onsen

Inside the bathing area, the steam is so thick you can barely see the bath. The bath is divided into two parts - one at a medium temperature, and the other zone (smaller) is really hot. The color is milky blue, with a slightly sulfuric smell. One window is fully open, so breathing is pretty comfortable. Small merchandise towels are sold for 200, no large towels for rent. The onsen is old-school, but I wouldn't say it's completely ancient - I liked it.