A beautiful example of what a supersento should be. I recommend Yu no Karo for a first supersento experience. The interior bating area is standard, if not a bit dark. Outside, the centerpiece is a large shallow rock lined hot spring bath. The hot, opaque, yellowish-brown spring water leaves a mineral buildup along the tubs and walkways. The spring feels like very diluted clay and does a great job relaxing your mind and body. The water here is similar to Amayu House, Kua Mukogawa, and Arima Onsen. Yu no Karo is also a good example of what a high osmotic pressure spring looks like. Besides the hot spring filled baths, the rest of the baths are filled with soft water from a well on site. The showers also use this soft water.
I come to Yu no Karo for their extra hot bath. Always about 46 degrees, extra hot baths are the best for my often aching back.
On the downside, Yu no Karo is often busy. Recently it's been showing it's age and the wear and tear that comes with heavy use. It’s still a great bath and right next to a wonderful shopping center with one of Kansai's largest 100 Yen Shops. Yu no Karo has a unique and confusing locker room system. After buying a ticket from the vending machine and present it to the front staff you will get a credit card sized piece of plastic with a number on it. In the locker room you can insert that card into any available locker.
Update 2018: Has been remodeled. Have not been back to see it yet.