It is a Ryokan with Onsen(hot spring).
The inn founded around 1716-1735 and the building is registered as a tangible cultural property of Japan.
Better to book with dinner and breakfast because there are not many places for dinner(the owner told me that they also can serve western style breakfast, if the guests wish and when they are not busy).
Access:
10mins walk from Miyazu station.
If you are taking the express bus from Kyoto or Osaka, you can get off at Kisenba-minato-kan bus stop(one stop after the Miyazu station) and walk about 3mins.
You can book from booking.com or Rakuten Travel and so on.