After meeting a bunny girl in a library, Sakuta Azusagawa finds happiness in his relationship with Mai Sakurajima, only to have his world turned upside down by the return of his first crush, the adult Shouko Makinohara. As if that wasn't enough, encountering a sick middle school Shouko triggers strange reactions in him. Now, faced with conflicting emotions and the responsibility for Shouko's well-being, Sakuta must navigate a complex web of relationships and choices that will challenge him to his core.