Yunomine Onsen Tsuboyu is a historic hot spring located in Yunomine Onsen, Japan. It is known for its unique outdoor bath, which is one of the few places where visitors can enjoy a private onsen experience. The bath is fed by natural mineral-rich waters, believed to have healing properties. The facility is small and can accommodate only a few people at a time, making it an intimate setting for relaxation. Visitors can enjoy the serene surroundings while soaking in the warm waters, which are a part of the Kumano Kodo pilgrimage route, adding to its cultural significance.