The spa is usually crowded with the monkeys bathing to keep warm in winter time. Like humans do, they shut their eyes just having a relaxing time and a great contrast between their red faces and white snows is so funny.
Yudanaka Onsen Spa is currently offering "Spa Tour Pass" which you can use for getting the spas in ryokans and hotels that are not available to the public usually.
Stay at Uotoshi Ryokan, go to Yudanaka Onsen Spa, and you may have a chance to share the bath with monkeys.
