Fukuchiyama Onsen is a recommended rural supersento to keep in mind if you are in the area. The indoor area has a good selection of baths while the outside has a few shallow hot spring baths set in a Japanese style garden with lots of large exposed rock. I wish they had spent more of that space putting a few more baths, as most of the rotenburo area is roped off garden. On the other hand, up a rocky path is a cedar bathtub that really feels removed from all civilization. I did go late in the evening in the winter so it was quite dark which enhanced the effect.
Fukuchiyama Onsen is built in a unique manner. The restaurant, omiyage shop, break room and entrance is built into a large traditional Japanese house. The baths are connected to that house via a hallway in a new building.
I went on December 30th so the bath was filled with relatives visiting for the New Year’s celebrations. One 5-year-old boy ran up to me, touched my chest hair, and asked “Why do you have all this hair?”
Surprised I replied, “Cause I’m an American.”
I should have said that I was a scary bear or something better. Also, not all Americans are as hairy as I am. I do not want to stereotype.
I can imagine that the baths here would have been more relaxing if the tons of people were not there. Still I remember how much I enjoyed it and I would like to go back if given the chance.
Good luck getting here without using a taxi from the station if you are not driving. This is a car only place.
Review Update January 2020:
This is a beautiful supersento located in the hills above downtown Fukuchiyama. I came back here for my second visit because I did not get a photo during the first. The baths are built into an old farmhouse. The buildings and gardens are why you would come all the way from Kobe or Osaka to visit. To get it out of the way, the hot spring here is completely apparent on the skin, to the eye or in smell. I will admit that after the bath there was some effect on my skin. My advice is to come here for the outstanding facilities that make up for the middling spring. Fukuchiyama has probably the best steam bath I have experienced. The steam, when it gets going, is so thick you can barely see. Great for clearing out your stuffy nose. The sauna was also quite hot. Outdoors there are two baths; a rock lined one and a rectangle shaped hinoki bath. Year round the gardens here are outstanding beating out some of the fancy Ryokan I have visited. Lastly, out front there is a huge pot where they prompt you to climb inside and take a photo! I learned that Fukuchiyama Onsen is owned by the same people as Toji (or whatever it is called) up near the Aeon Kita-Kobe Mall. Both have beautiful buildings, the latter being purpose built and newer, but both have generally disappointing springs. I would still recommend visiting If you find yourself in Fukuchiyama as this is probably the best option for a natural hot spring supersento in the area.