Okumizuma Onsen

Nestled in the mountains of Kaizuka City, Osaka, along the Mizuma stream, Okumizuma Onsen is a solitary ryokan discovered in 1943 when a geological survey found a layer of sodium bicarbonate water underground and subsequent drilling brought the spring to the surface. Used as a public rest facility after the war, it is now known as the hidden retreat of Senshu.

The water is a sodium bicarbonate spring with a source temperature of 19.3°C and a nearly neutral pH of 7.1, warmed before use to about 40°C indoors and 42°C in the open-air bath. Its gentle, silky quality has earned it the nicknames beauty bath and miracle bath.

The stone bathhouse features indoor and open-air baths, plus rooms with private open-air tubs. Kaiseki cuisine and the inn's signature hot-spring tofu are highlights, with day-use bathing available for 1,100 yen (11:00-20:00; bathing-only visits unavailable on weekends and holidays).