Six months ago, Sakuta Azusagawa had a chance encounter with a bunny girl in a library. Ever since then, he’s been blissfully happy with his girlfriend: Mai Sakurajima, that same bunny girl. However, the reappearance of his mysterious first crush, the now-adult Shouko Makinohara, adds a new complication to his relationship with Mai. To make matters worse, he then encounters a middle school Shouko in the hospital, suffering from a grave illness. Mysteriously, his old scars begin throbbing whenever he’s near her.