Oniiwa Onsen is a hot spring town in Gifu, Japan. The water leaves the ground at 17.3–36.6°C, comfortably warm. Officially the water is classed as sulfur spring and radioactive spring. 3 inns take visitors here.
The classic rotten-egg smell and milky white water. It can tarnish silver jewellery, so take it off.
Radioactive spring 放射能泉
Contains trace radon that leaves the water quickly. Also called radium or radon springs.
With tattoos
Many public baths still turn away visible tattoos, and the rule is set by each bath, not by the town. The reliable way round it is to bathe privately: a room with its own open-air bath, or an inn with a private bath you can book for yourselves.