Sainokawara Open-Air Bath - A Tattoo-Friendly Hot Spring in Kusatsu Onsen, Gunma

Sulfur hits you first — sharp and unmistakable — as you walk the stone path through Sainokawara Park. Hot water seeps from the ground on either side, steaming between the rocks, pooling in the riverbed. Then the bath itself opens up ahead of you, and the scale registers: a single enormous pool stretching across the valley floor, steam rising into the forest canopy above.

Sainokawara is one of Japan's largest outdoor baths, fed by Kusatsu's powerful Bandai source spring. The water runs hot near the inlet and gradually cools as it spreads outward, so you find your own temperature by moving through the pool. There are no showers, no washing stations, no indoor facilities. You soak, you rest on the submerged stone platforms, you watch the season change the trees around you.

The walk from Yubatake through the park is part of the experience. Hot streams cross the path, steam drifts between the trees, and by the time you reach the entrance you've already been inside Kusatsu's volcanic landscape for ten minutes. If you want an outdoor bath that feels like bathing in the mountain itself, this is the one. Guest reviews confirm tattooed visitors bathe here openly.

• Tattoos Accepted, No Questions: Years of guest reviews in English and Japanese confirm tattooed bathers soak in the communal pool without covers, patches, or hesitation from staff.
• Scale You Won't Find Elsewhere: The pool spans roughly 500 square meters — large enough that even on busy days you can find space and quiet at the far edges.
• Choose Your Own Temperature: Water arrives near boiling from the Bandai source and cools as it flows outward. Move through the pool to find the heat that suits you — no two spots feel the same.
• The Walk In Is Half the Experience: The path from Yubatake through Sainokawara Park passes steaming hot springs, geothermal pools, and warm streams — ten minutes of volcanic landscape before you even reach the bath.

The heat finds you before you settle in — acidic water with a mineral bite that sharpens against cool mountain air. The pool is rough-hewn stone, wide enough that the far edge disappears into steam on humid mornings. Near the source, the water runs hot enough to make you flinch. Drift toward the outer edges and it softens to a long-soak temperature where an hour passes without thinking.

Submerged stone platforms sit partway in the water, just enough to rest on between rounds. The pool is gender-separated, open to the sky, and ringed by forest on all sides. In winter, snow collects on the rocks beside you while the water stays hot. In autumn, the canopy overhead turns red and gold. There are no showers and no soap — just the spring, the stone, and the valley. Bring your own towel and come ready to soak, not scrub.