Kaisei-yu

Kaisei-yu is at 5-10-5 Nishi-Kamata, Ota, about seven minutes on foot from Kamata Station. The black-water bath, a black-water bath with added carbonation and an aquarium beside the bathing area distinguish it from the nearby Hasunuma and Kamata Onsen baths. The Ota tourism association lists 15:00–23:30, closed Fridays. Primary tourism and railway-operator information checked 1 November 2026. Those sources do not settle the current admission price, tattoo rules or sauna availability; this entry does not certify them. Bring or check the availability of washing supplies before visiting.

Directory reference, not live inventory. Confirm current prices, product availability and visiting rules with the operator before buying or travelling.