This supersento is just beautiful--as all of the Happu no Yu chain is. You'll pay extra but get quality service and furnishings. The baths say there is 4 different types of spring but they only have documentation for a single spring. I don't really know what they are doing with the spring. That said, no matter which bath, the spring water is pretty brilliant. The baths and locker rooms don't really take that much space over all in this massive complex. That said, the design is well thought out and there are many fun places to discover in the baths even on a somewhat busy evening. In the outdoor bath look for the little bits of orange-brown mineral "yu no hana" on the bottom of the bath.