Tsubaki starts off her brand-new high school life the right way—by visiting an onsen! In the bath, she has a chance encounter with a beautiful black-haired goddess.

"Won't you come to an onsen with me?" Pursuing her with fervor, is it possible to have a relationship with someone before you even become friends? This is the story of two girls who love the onsen and the ups-and-downs of their hot spring days.

Note: Chapter count includes 4 extras.