|“||I can't allow any of that... The world must be a paradise...||”|
Thorn is the leader of the Ostinato Musicians. She serves as the primary antagonist of the game and the penultimate boss.
In Mobius, Thorn appears as a woman who, according to Shogo Satake, appears identical to Ichika Saotome. She possesses long black hair that falls past her shoulders and covers the right side of her face with a hair clip above her left ear. She wears the school uniform, though her bow is slightly larger with a polka-dot design on it. She also carries with her a pointing stick at all times.
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.
"Also... the Hidden? Couldn't that be something even you don't want to know?"
The following content contains spoilers. Please proceed at your own risk.
When revealed to be Asuka Natsume, she reveals to also bear a deep grudge against Shogo, having orchestrated events so that Mobius would become his own personal hell. She event so far as to take on the appearance of Ichika, a close friend of hers, just to spite him. Wheras Ichika's death has traumatized Shogo immensely, it has done nothing but fill Thorn with anger: both at Shogo and the world.
Due to Ichika's aforementioned suicide, Thorn desired the destruction of the world. Showing off her cunning nature, she was easily able to warp μ's desires in granting wishes in favor for her own: that being the destruction of the world by using the Ostinato Musicians' concerts to fill her with negative energy.
Asuka Natsume's history is unknown, other than that he was close friends with a girl named Ichika Saotome and Shogo Satake thirteen years prior to the events of the game. They greatly enjoyed attending concerts at the Grand Guignol, though one day, Ichika and Shogo attempted to commit double-suicide. Shogo had backed out of the idea at the last possible second, a decision which has haunted him since. Asuka, however, was enraged and swore to make Shogo's life a living hell.
At some point in time, Asuka discovered Mobius and became Thorn, modeling his appearance after the deceased Ichika. When she discovered that Shogo had also entered this world, she began to orchestrate a series of events to follow through with her promise while also attempting to have μ grant her own wish. By her own suggestion, μ founded the Ostinato Musicians, who then began concerts that would slowly begin to fill μ with negative energy, thereby warping her view on reality and make her much more willing to comply with the wish of destroying reality.