Tennen Onsen Naniwanoyu

Naniwanoyu is an eight-floor day-use bathhouse in central Osaka, with its main baths and open-air area near the top of the building. The onsen water is a sodium chloride-bicarbonate spring known locally as bijin-yu (美人湯, beauty water), and bathers describe it as soft on the skin. Alongside the source-water baths there's a big Bali-style rock bath, a lie-down bath where warm water runs over a textured floor, a seated bath that lets you soak your feet while water flows down your back, and an artificial carbonated bath kept deliberately mild so the bubbles don't dissipate. On the sauna side there's an infrared sauna with steam bursts on a timer on each side, a salt sauna, a steam sauna, and on the women's side a collagen-light steam room, plus a jet-equipped cold bath to finish. The open-air floor sits high enough above the streets that it's easy to forget you're in the middle of the city. There's a tatami rest area for lying flat after a soak, two in-house restaurants if you just want to eat without bathing, and parking shared with the pachinko hall in the same building.