Thorn is the leader of the Ostinato Musicians. She serves as the primary antagonist of the game and the penultimate boss. As both an Ostinato Musician, as well as the leader of the organization, Thorn is strict and no-nonsense on top of being very serious. Following Kensuke Hibiki's defection and the emergence of the Going-Home Club, she immediately regarded them as a threat to their "paradise." She especially considers the protagonist to be dangerous, as he was the first to develop the Catharsis Effect and enlisted the aid of Aria.