After Suzuhara Hibiki recites a spell at a secluded onsen marked on a map entrusted to him by his late granfather, a resident of the onsen world, Mahiru, suddenly appears.Realizing she can't return to her world, she decides to live together with Hibiki.On their way back, they run into the class president Fujishiro Yukari, proprietress of an onsen inn, with another spirit of the onsen world as its guardian...A romantic comedy of three students and two guardians of onsen interweaves with a misterious story of onsen...