Louise Halevy begins as an AEU exchange aeronautics student from a wealthy Spanish family, studying in Japan and dating her classmate Saji Crossroad. Spoiled, stubborn, and used to getting her way, she is possessive of Saji and often manipulative, yet she does care for him and her family deeply. Her life is shattered when Gundam Throne meister Nena Trinity attacks a family wedding, killing all of Louise’s relatives and destroying her left hand with red GN particles, which cannot be regenerated. Broken by the trauma, she ends her relationship with Saji to free him for his dream of working in space.

Four years later, Louise has inherited the Halevy fortune and become a sponsor of the A-Laws, a brutal peacekeeping force, after being recruited by Regene Regetta and Ribbons Almark. Ribbons exploits her desire for revenge and attempts to turn her into the first purebred Innovator, giving her pills that enhance her physical abilities at the cost of slowly deteriorating her body. She becomes a mobile suit pilot, fighting with intense hatred for Celestial Being and the Gundams, believing they robbed her of everything. Her hatred deepens when she discovers that Saji is assisting Celestial Being, and she nearly kills him during the final battle, but stops when she sees he still wears her engagement ring, overwhelming her with memories. Ultimately, she abandons her revenge and rekindles her relationship with Saji, though she is left with chronic post‑traumatic stress and a mechanical prosthetic arm. Notable abilities include her piloting skills in the mobile armor Regnant and her fluency in Spanish, as well as the financial power she uses to support A-Laws mobile suit development. Her journey is one of a victim of war turned into a weapon of vengeance, and finally finding a fragile peace.