麻生釣温泉 亀山の湯

This self-catering inn near the Oita-Kumamoto border is built as a cluster of detached cottages, each housing its own private bath. There are more than a dozen baths across four styles: barrel, rock, cut-stone, and hinoki (檜) cypress, and several of the hinoki baths sit right inside the guest room. Two hot springs feed them through a coin-timer system that lets in fresh water with every soak. There's no meal service; guests cook for themselves at an on-site jigoku-mushi (地獄蒸し) steam kiln, using the geothermal steam for eggs, vegetables, and whatever they've brought. It's a quiet place, the kind where you wake up to birdsong.