Fiasse Christella is an English woman born January 24th. She has blonde hair, blue eyes, blood type O, stands 1.60 meters tall, and has measurements of 93-60-90. Fiasse heads the prestigious Christella Music Academy in England, a family-founded institution. Her father, Albert Christella, served in the British House of Lords. Her mother, Tiore, was a world-renowned singer; Fiasse inherited both her vocal talents and a significant inheritance from Tiore.

During childhood, Fiasse endured the traumatic killing of her father and his bodyguard, Shirō Fuwa, by a terrorist organization marked by a clover leaf symbol. Initially blaming herself, she later formed close bonds with Shirō's children, Kyōya and Miyuki Takamachi (who took their mother's surname), maintaining strong family ties. Spurred by this tragedy, Fiasse resolved to wield her singing talent for charity, organizing annual world tours through her academy.

As an adult, the same terrorist organization targeted Fiasse, seeking her mother's inheritance. Despite having a professional bodyguard, Ellis McGaren, Fiasse proactively enlisted her childhood friends Kyōya and Miyuki—both trained swordsmen—for additional protection due to their shared history and her trust in them, causing friction with Ellis. Fiasse insisted on continuing her charity tours despite escalating threats, demonstrating her commitment to the mission. She possesses a calm and gentle personality but is determined when pursuing goals. Fluent in Japanese from her long connection to the Takamachi family, Fiasse remained the focal point of protection efforts, her safety tied to unresolved past events. The terrorist threats specifically targeted her inheritance and international charity work, forcing her security team to confront both physical dangers and emotional tensions rooted in their shared history.