Yamaga Kazenosato

Yamaga Kazenosato is a small hot-spring inn in the hills above Kitsuki, in an area that was once a mining town for gold, silver and copper. The bathing here centers on a tub bath fed straight from the spring: the water runs a deep brown with a strong, distinct smell, and it stays cool rather than hot, so several reviewers describe it as bracingly cold rather than a typical soak. Alongside it there's an open-air bath, a dry sauna, a cold-water bath, and an indoor bath that swaps daily between two rooms, Buzen no Yu (豊前の湯) and Bungo no Yu (豊後の湯). One of the cottage-style guest rooms has its own onsen bath; the other room types don't. There's a restaurant on site as well.