Hanayama no Yu has great soft water in the normal baths leaves your skin slippery soft and an equally good spring water in the rotenburo which is just as clear and soft feeling
There are two different bathing areas that change from men to women each day. They both have a wooden and stone motif. All of the wood looks fresh and alive while the stones show their age with grace. The tiles on the floor have just enough grip yet feel smooth and are great on your feet. The jet bath has my favorite single and sunflower styles.
As I said with the baths everything is really clean. It might not seem that way from the outside, and the golf driving range isn't the most beautiful thing, but inside everything seems right to me. It's not the biggest supersento and you might bump into someone on occasion. The sauna can fit 3~4 people maximum. Also soap from the showers pools up on the floor and doesn't drain well so make sure to rinse it off after you wash yourself to be polite.
I had a great chat with some of the customers in the sento. The view from the outdoor area is just a some rice fields and some forested hills. Not much too look at. There always seems to be a cool breeze which helps make this place seem fresh. It's easy for me to stay for a while, but for those with kids they might get bored fast here. It's too peaceful.
There is a golf driving range in the same building as the sento. They have club rentals if you want to hit a few balls. I've only been here in the afternoon and I have to say that a lot of the appeal of this onsen is how bright and refreshing it is in the afternoon. I totally recommend going there on a sunny day.
Update Winter 2018: Still great!