Isabelle Müller, wife of former military pilot and Pathfinder Air Race competitor Lewis Müller, possesses long brown hair, brown eyes, and a distinctive mole beneath her left eye. Her attire typically includes a sleeveless yellow dress paired with gold earrings and white high-heel shoes. Calm and soft-spoken, she contrasts her husband’s brash demeanor, with her composed nature bolstered by adept acting skills.

After Sam Ibrahim orchestrated an accident that left Lewis severely injured and wheelchair-bound, Isabelle became his primary caregiver, managing daily responsibilities while nurturing a deep-seated resentment toward Sam. Her history intertwines with Laurent Thierry’s scheme targeting the Ibrahim brothers. Though Lewis declined involvement due to moral reservations, he permitted Isabelle to collaborate with Laurent, recognizing her shared animosity toward Sam.

During the Singapore Sky arc, Isabelle posed as a grieving widow to manipulate Clark Ibrahim, employing her theatrical talents to facilitate Makoto Edamura’s infiltration as Clark’s mechanic. She feigned emotional distress, accusing Clark of sabotaging Lewis’s plane—a calculated move aligning with Laurent’s strategy to expose the brothers’ corruption. Her actions exemplified a pragmatic pursuit of justice for Lewis, intertwining personal vengeance with methodical participation in the con.