Story
The Onsen Musume who make their homes in locations throughout Japan are deities who were born when water first began gushing out from the sources of hot springs. Their appearance is no different from that of a human. On most days, they attend Onsen Musume Normal School on the island of Odaiba, where they study "Onsenology," the science of hot springs. They live in ryokan in their hometowns. After school and on days off, they help out at the ryokan, as well as in places such as the tourist information centers in hot spring areas. In order to create excitement in hot spring areas throughout Japan that have started to see dwindling numbers of tourists, the Onsen Musume are instructed by Sukunahiko, the highest-ranking hot spring deity, to work as idols. This leads the Onsen Musume to form a number of different groups and spread the word about their hot spring areas through song, dance, and on occasion, other extracurricular activities.

Onsen Musume is a multimedia regional revitalization project that hopes to increase tourism to onsen (Japanese hot springs) by anthropomorphizing onsen as anime characters, and creating anime, manga, and video games about them.