Akane
I've heard that there's a spa pass for Oku Hida Onsen called a “Yukemuri Tegata” although I may be mistaken about the Japanese name. Where can I buy this pass?
Akane
You can buy it any of the participating hotspring facilities. There's a list on this website. And by the way it's called “Yukemuri Tatsujin”.
http://www.okuhida.or.jp/en/yukemuri
