Hana no Yu has a strong "bathing for health" feel. Maybe because I went there in the afternoon, the bath was filled with seniors. The hot spring here is a radon spring which is popular among those bathing to prevent or recover from disease. The baths are large and there's a wide open rotenburo with a very big bath. For the price it's a great bathing experience. Despite it's inconvenient location it's worth figuring out where this one is. If I lived in the neighborhood it would be my local bathing spot.

Update September 2018: Went here with another family after a group hike. I can reconfirm that the cost performance here is outstanding. Good place to take children also.

Update Summer 2021: They have done a major remodel here since my last visit. Baths are still the same and fed with the above average, smooth feeling radon spring. However, the entrance, hall and changing rooms have been totally redone. Much nicer than before. Love the new sign in the entrance!
There is a place to fill your bottles with the radon spring water now. Daily recommended amount is 500ml.