Kusatsu Onsen is a famous hot spring with the largest amount of natural hot water in Japan. In the center of the town is Yubatake, the largest hot spring supplying Kusatsu Onsen, with cascading gushes of spring water of as much as 4,000 liters per minute. This dynamic, overwhelming display is a must see.
Netsu-no-Yu is a facility where you can experience yumomi, the traditional process of lowering the temperature of the hot water by stirring it with wooden blades about 1.8 meters long so as not to lose the good benefits of the hot spring water of Kusatsu Onsen by diluting it with cold water.
The water of Kusatsu Onsen is highly acidic and is said to melt a one-yen coin in one week and a big nail in ten days. Th e water is very beneficial; the only disease it cannot cure is said to be lovesickness. There are many day-trip bathing facilities and public baths. Don’t forget to try onsen manju (Japanese steamed cake with a sweet red bean paste filling) and onsen tamago (eggs slowly cooked in hot springs to the point where the whites are still soft but the yolks are slightly hardened) with a custard cream-like texture.
Yugama is a crater lake located at the top of Mt. Shirane about 30 minutes from Kusatsu Onsen by bus. The strongly acidic lake (pH 1.2) is a beautiful emerald green seen against the backdrop of the stark landscape. The mountains are dotted with ski slopes, so this area is also a good place for winter sports.
To the east of Kusatsu Onsen is Shima Onsen, surrounded by mountains. Yamaguchi Rotenburo (open-air bath) along the river is a free public bath open to anyone. The water of Shima Onsen is good for drinking and is believed to cure stomach and intestinal problems. At various locations in the town, you can find places to drink the hot spring water. Don’t drink too much at first. Try a bit and see how you feel. Dishes made with the freshwater fish from the Shima River are a must. There are many different types of hotels in this area, from traditional ryokan (Japanese-style hotels) to modern hotels.