For most travelers in Japan, the highlight of a trip to the hot springs is the rotenburo, or open-air bath. The idea of an alfresco dip is so appealing that drawing visitors to your hot spring inn or hotel becomes several degrees harder if you don’t have outdoor tubs.
But you shouldn’t write off indoor hot springs entirely, as they boast a couple of advantages. Having a roof over your head makes them a good choice for a rainy day, and being climate controlled means less shivering once you step out of the water. Plus, if you’re heading to Gunma Prefecture, soon one indoor hot spring will give you the chance to soak in the company of Hello Kitty.