The hot spring facility in Hiruzen Kogen Sports Park. The hot spring water contains weak radiation, and hydrogen carbonate springs are said to be effective for neuralgia, muscular pain, and skin diseases. Get rid of your fatigue and refresh your body with one of the best natural radon hot springs in Japan. In addition to a large bath, a jacuzzi, sauna, and three open-air baths are available. Each open-air bath offers views of Hiruzen's scenery and beautiful Japanese gardens, allowing you to enjoy the four seasons of Hiruzen. The rest area is also available in the facility.