Otaki no Yu Onsen - A Tattoo-Friendly Hot Spring in Kusatsu Onsen, Gunma

Sulfur hits you before you step through the door. Inside, the main bathhouse opens tall — wooden pillars rising through steam, daylight catching the milky surface of the water. But the real draw is downstairs. A staircase leads to the awase-yu, a basement chamber where a series of pools sit side by side, each hotter than the last — starting at a gentle 38°C and climbing to a punishing 46°C that most bathers hold for seconds before retreating to the cold plunge.

Otaki no Yu runs on Kusatsu's Nikawa source, one of the town's most potent springs. The water is strongly acidic, sulfur-heavy, and leaves your skin noticeably smoother when you towel off. Among Kusatsu's three main public baths, this is the only one with a sauna, cold plunge, and the awase-yu progression. Tattooed guests bathe openly here — confirmed across years of visitor accounts in both English and Japanese. If you're spending a day in Kusatsu and want one bath that gives you the full range of what this town's water can do, this is the one.

• Awase-yu Temperature Progression: A series of pools rising from 38°C to 46°C — an ancient Kusatsu bathing method that walks your body through escalating heat, ending with a cold plunge that resets everything.
• Tattoos Accepted, No Covers Needed: Tattooed guests bathe in all communal areas without restriction — confirmed by visitors in English and Japanese across multiple years of reviews.
• Kusatsu's Nikawa Source: Draws from one of Kusatsu's most prized springs — strongly acidic sulfur water that turns milky white and leaves skin noticeably soft.
• International Visitor Friendly: English signage and instructions throughout, with staff who can communicate the basics — visitors consistently describe the place as approachable for first-timers.

The water is white. A cloudy, sulfur-heavy white that you smell before you touch, fed by the Nikawa source at a pH acidic enough to tingle on fresh skin. The main indoor bath is wide and bright, with tall wooden pillars and natural light — a good place to ease in. Outside, a rock-lined rotenburo lets you soak with cold air on your shoulders, especially sharp in winter when snow settles on the stones around you.

Then there's the awase-yu. Down a staircase, the basement chamber is dimmer, the air thicker with steam. You start in the mildest pool and work your way up. By the third or fourth, the heat is serious. The final pool is a dare — most bathers manage seconds before pulling out. The cold plunge afterward is the payoff, and regular bathers say it's what keeps them coming back.