Sayo was supposed to visit a hot spring inn with her husband, but ended up going alone due to certain circumstances. Coincidentally, married woman Mio also arrived at the same inn by herself. Bi-sexual Sayo sensed that Mio had lesbian experience, and gradually drew closer to her. The two grew increasingly attracted to each other, cherishing their nights together as they built a passionate relationship. As the brief summer drew to a close, their love affair naturally came to an end.