Ashiyu: Foot Spa
Similar to onsen, these hot foot spas include hot sulfur water. The footbath, called ashiyu are quick to visit and most of them are free. If you are lucky you can find one next railway station. Nearby there is usually a vending machine where you can buy a towel for 100 yen.
In mountainous areas its easy to find these ultimately relaxing places. Usually they are next to onsen. Even in wintertime the water is warm. Therefore you can enjoy most ashiyu through the seasons.
You can dip your feet in the water ankle deep. It really relieve your weariness after long walk in the mountain. Some places offer also a "foot massage course" free of charge.