Rosenkreuz

Phantom thief Rosenkreutz, who disturbs the great power of Fahrenheit. His true identity was Cecil, the son of the current emperor's mistress, the Marchioness of Hanover, with her ex-husband. He hides his gender and marries Oscar, the Chancellor of his neighboring country of Aquitaine, as a substitute for his poisoned half-sister of imperial blood. Cecil had suspected him as the mastermind of the assassination, but gradually became attracted to Oscar's humanity. Source: MU