A visit to Takaragawa Onsen is a treat in any season but is especially rewarding in winter. Head out into the mountains from Minakami and sitting on a remote stretch of river is the old ryokan, Osenkaku, and the hot spring baths which are some of Japan’s largest outdoor onsen. They are beautiful facilities in a stunning natural setting.
Even if you are not staying in the ryokan you can go there to experience the baths. They are unusual in that they are still mixed, but there is also a separate female facility if that is more to your liking.
Whether you stay (highly recommended) or just go to the baths, this is an amazing experience, and you will quickly realize why it is rated up there as one of the very best destinations in the whole of the country.