A hot spring located in the middle of Garandake, an active volcano. The spring water is very unique because it has high acidity and contains the second highest concentration of aluminum ion and the largest iron ion content in Japan. Its highly acidic hot spring water, which is supposed to be several tens of times stronger than that of lemon, does not cause soap to form bubbles, and you may feel the acidity on your skin when entering the bath. It is effective against skin problems such as atopic dermatitis, and many visitors come from all over Japan because of this beneficial effect. There are 3 types of baths: indoor bath, outdoor bath, and a family bath. Also, Garandake crater can be reached about 5 minutes on foot from the hot spring, where guests can see the dynamic appearance of the fumarole.