Whilst in Sounkyo I made a point to frequent the Onsens. Sounkyo, I would guess was built on Onsens and has numerous. I managed to only visit 3 as Kurodake no Yu, the one down the road from where I was staying, was great and you could get an onsen and ramen for ¥980. Choyo Tei & Choyo Resort Hotel are the other 2 I visited.
Onsens are a great place to soak up Japanese culture and relax after a busy day and are definitely worth visiting. If you want to read more about Onsens why not go over to nisekosnow.net and check out our article on Onsens and also check out the Onsen etiquette page if it is your first time.