Rokko Otomezuka Onsen is a Nada-ward bathhouse that pours its own carbonated hot spring, 480 litres a minute, into the baths without adding water or heat. Its two bath halls swap between men and women daily: one has a high-temperature sauna and the other a salt sauna, both with open-air onsen baths. Entry is ¥500 plus ¥300 for the sauna. Open every day from 6:00 to 1:00.