Kunimi Onsen is a mountain hot spring retreat located at an elevation of approximately 850 meters in the Ou Mountain Range in Shizukuishi Town, Iwate District, Iwate Prefecture, near the border with Akita Prefecture. As a lush hot spring resort within Towada-Hachimantai National Park, it is renowned for its rare and vivid emerald green hot spring water. Known as "Yakushi-no-yu" (Medicine Hot Spring) since the Edo period, this historic famous hot spring served as a therapeutic bathing facility for the Nambu Domain and continues to attract many therapeutic bathers due to its high efficacy.

The hot spring is said to be beneficial for chronic gastrointestinal disorders, neuralgia, rheumatism, and skin diseases, with particular effectiveness for chronic skin conditions and gynecological ailments. As a hydrogen carbonate spring, it has cleansing properties for the skin and provides a refreshing sensation after bathing, reportedly making the skin smoother. The water is also potable, with one cup said to be good for gastrointestinal disorders, though it is famously known for its extremely unpleasant taste.

All facilities close during winter, operating seasonally from mid-May to early November.

Overnight accommodation is not available, and the wooden parts of the buildings are scheduled to be demolished by 2025.