It was her 16th birthday when Kurusu's classmate, Ogami, confessed to her. She’s delighted, but also feels very uncomfortable in relation to her friend Kiraha, whom she knows has a soft spot for this guy. But Kurusu doesn’t have any time to rejoice, because mysterious evil creatures suddenly appear and attack her!! Kurusu must face her destiny along with Ogami, whose role is to protect her. However, they can't tell Kiraha about the situation.