Tennokawa Onsen Center, known as Kigi-no-Yu (Wood-Wood Hot Spring), is a village-operated day-trip bathing facility located in Tsubonouchi, Tenkawa Village, Yoshino District, Nara Prefecture. Established in 1987, it stands near the revered Tenkawa Daibenzaiten Shrine and has served as a place of relaxation in this village steeped in Shugendo mountain asceticism and ancient mythology. The facility was renovated in partnership with the Yamato Forest Management Association, embracing the concept of connecting mountains and daily life through bathing, while embodying the sustainable cycle of forest resources.

The spring water is classified as a sodium bicarbonate spring with a source temperature of 16.1 degrees Celsius and a pH of 8.56, making it mildly alkaline. The water is colorless, transparent, odorless, with a faint saline taste. It is renowned as a beauty spring for its smooth, silky feel on the skin. The facility heats its water using a gasifier, a high-efficiency wood-burning boiler that utilizes thinned timber from Tenkawa Village forests, harmonizing forest conservation with onsen management.

The building is a single-story wooden structure generously built with Yoshino cedar, Japanese cypress, pine, and maple, with a grand maple pillar standing at the entrance. The indoor bath features a luxurious tub rimmed with Koya maki (Japanese umbrella pine) over 30 centimeters wide, with a cypress wood bottom. Wooden buckets and cypress stools carry the wood theme through every detail. The outdoor bath is sheltered by an azumaya pavilion, offering views of the surrounding Tenkawa mountains.