Located on the third floor of the main building of Kyukamura Hiruzen Kogen, Kogen no Yu is a hot spring facility that draws water from a simple, weakly radioactive spring containing natural radon. From the large bath, you can enjoy a panoramic view of the mountain ranges of Kami-Hiruzen, Naka-Hiruzen, and Shimo-Hiruzen, as well as the idyllic scenery of the Hiruzen Kogen Plateau, and you can relax while enjoying the seasonal scenery.

The spring quality is a "simple, weakly radioactive spring (radon spring)" that is said to be effective for neuralgia, muscle pain, joint pain, and poor circulation, and is known as a "beautiful skin bath" because it leaves your skin feeling moisturized after bathing. The indoor bath is also spacious, and amenities such as shampoo, conditioner, and body soap are provided, so it is easy to stop by even if you come empty-handed.

In the summer, there are many camping facilities in the area, so many campers use the bath.

If you're going on a date, there is a Bell of Love on the nearby Shirakaba Hill.

[Trivia]
The natural radon hot springs of the Hiruzen Plateau are simple, weakly radioactive springs that are expected to have a "hormesis effect." Trace amounts of radon radiation promote blood circulation and leave the skin feeling moisturized after bathing, so they are also said to have a "skin-beautifying effect."