While perusing the local library, Sakuta Azusagawa stumbles upon a peculiar sight—a bunny girl wandering the aisles. To his astonishment, this bunny girl happens to be none other than his famous senior, Mai Sakurajima. As Sakuta realizes he is the sole witness of her presence, he seizes the chance to assist her. Mai's cryptic dilemma resonates with Sakuta, drawing parallels to his own and his sister's struggles, all linked to the enigmatic 'Adolescence Syndrome' that twists the fates of young individuals. With Mai's condition deteriorating, Sakuta delves into unraveling the mystery behind her gradual vanishing act from the public eye, determined to find a remedy before it's too late.