Houunkaku is a rustic hot springs inn located in mountainous Onikobe. It is famous for its Taki no Yu, an open-air bath formed at the base of a small waterfall, naturally hot due to the mild volcanic activity of the area. The inn makes a great base for casually exploring the area's other volcanic attractions, as the Onikobe geyser park and the Onikobe Jigokudani Nature Trail are located just a few minutes' walk from the inn.

There’s no barrier between waterfall and bath, so bathers can sit as close to the falls as they like. The baths here are open to day-trippers as well as overnight guests. The indoor baths are gender-separated, but Taki no Yu is a mixed-gender bath. Modest bathers needn't worry—towels or hotel-provided modesty bathing garments can be worn into Taki no Yu.