Illyasviel "Illya" von Einzbern awakens disoriented and bewildered in a parallel Fuyuki City. Her home lies in ruins with a gaping hole at its center, and an unexpected snowfall only adds to her confusion. Without her friends and magical wand, Ruby, Illya feels a sense of loneliness as she tries to navigate her devastated surroundings. Suddenly, a girl named Tanaka, dressed in a gym uniform and suffering from memory loss, attacks Illya. Despite her own confusion, Tanaka claims to know the whereabouts of Illya's missing friends, including Rin Toosaka, Miyu Edelfelt, and others. As the Ainsworth family, who control their parallel universe, pursue them, Illya and Tanaka must team up to find a way back to their reality. Will they succeed in their mission, and how will Illya be able to restore her world to its previous state?