Matsuba Onsen Taki no Yu

Matsuba Onsen Taki no Yu is a hot spring inn tucked in the mountains along the Kogigawa River in Kotsumi, Kaizuka City, Osaka Prefecture. No primary source confirms exactly when the spring was first opened, but a guest wing with private open-air radon baths was added in January 2013, and the day-trip bathing facility appears to have served the local community for years before that. It sits about five minutes by car from Kaizuka Interchange on the Hanwa Expressway, making it an easy stop from central Osaka or Kansai International Airport.

The spring is classified as a simple weakly-radioactive spring (radon spring), rising from cracks in granite deep underground. The water is weakly alkaline at pH 8.4, with a source temperature of 26.8°C and a yield of 83.3 liters per minute. Because the source runs cool, the bathwater is heated, filtered and recirculated, and disinfected before use; the colorless, clear water is valued for the radon spring's characteristic ability to keep bathers warm long after leaving the tub.

The facility offers separate indoor baths and semi-open-air baths for men and women, while each of its six guest rooms comes with its own private open-air bath. Day-trip bathing costs 720 yen for adults and 350 yen for children, with the on-site restaurant 'Ogi' and a lounge available for guests. Overnight stays include two-meal plans, giving visitors a relaxing base from which to enjoy the sound of the Kogigawa River and its seasonal greenery.