Ciel displays blonde or golden hair complemented by a loose yellow cape, black beret, tight white trousers, and gray wide boots. Introduced as a wandering Magus singer radiating light-hearted charm, this persona masks her true function as an Ideal organization spy. Her core mission involves locating Histoire by investigating Noir, whom Ideal identifies as the key to accessing it. She infiltrates Rock Town, deliberately befriending Kanata and Noir while using her singing career as cover for surveillance. Genuine romantic feelings for Kanata emerge during this mission, conflicting sharply with her orders to eliminate him after delivering Noir. This internal struggle triggers profound hesitation and emotional turmoil. Her combat capabilities include channeling electrical energy to subdue targets, deployed both defensively and offensively in confrontations. Ciel's story reaches its climax when she sacrifices herself to evade capture by Ideal's leader, Weisheit Blaurecht. This act erases her personality and consciousness entirely, leaving her physical form barely functional. In the aftermath, Kanata activates a memory transfer protocol, moving Noir's consciousness from the dormant Mystere body into Ciel's vacant vessel. This fusion grants Noir autonomous existence independent of Mystere and unexpectedly immunizes her against global Magus deactivation events. Ciel's body becomes Noir's permanent host, terminating Ciel's individual existence while enabling Noir's continued survival and unique resistance to system-wide threats.