Maria Cadenzavna Eve, a Ukrainian national, endured childhood trauma from regional conflicts that destroyed her home and claimed her family. Forced into vagrancy with her younger sister Serena, both were taken into the White Orphanage for the Receptor Children project, undergoing experiments to induce Symphogear aptitude. Six years before the series, Maria witnessed Serena sacrifice herself using her Superb Song to defeat the Nephilim; Professor Nastassja lost the use of her legs during the same event while trying to save Maria. This loss deeply shaped Maria's motivations and sense of responsibility.

Initially an antagonist, Maria claimed to be Finé's newest reincarnation after Ryōko Sakurai's death. Wielding the Gungnir relic within the F.I.S. organization to prevent the moon's fall, she debuted as a top-ranking US idol. This led to a collaborative "Queens of Music" concert in Japan with Tsubasa Kazanari. Maria used the event as a double agent to awaken the Nephilim, yet ensured the audience's safe evacuation despite controlling attacking Noise. While projecting confidence and command, she privately grappled with guilt over causing harm, especially after Dr. Ver callously used Noise to kill children. Discovering Ver's true plan to destroy humanity ended her manipulation; she abandoned the Finé persona and allied with Section Two to stop him, surrendering willingly afterward.

Joining S.O.N.G. marked Maria's transition to a protagonist seeking redemption and honoring Serena's memory. She adopted the Airgetlám relic ("Silver Arm," named from Irish mythology), replacing Gungnir. Airgetlám wields a chain of daggers for offense and summons a protective shield. Her combat style blends blades, whips, and direct strikes, featuring attacks named Infinite†Crime, Empress†Rebellion, and Horizon†Cannon.

Within S.O.N.G., Maria became a stabilizing presence, offering emotional support and acting as a voice of reason. She formed a close bond with Tsubasa, relating to her loss and sometimes grounding her with a forehead flick, mirroring Kanade Amou's past gesture. Maria assumed a protective, maternal role towards Kirika Akatsuki and Shirabe Tsukuyomi, feeling responsible for their well-being, and cared for the ailing Nastassja as a mother figure. Despite projecting composure, she privately battled self-doubt about her strength compared to Symphogear users like Hibiki Tachibana and Tsubasa. Her determination to protect others remained steadfast. She continued her idol career, frequently performing duets with Tsubasa to inspire hope.

During XV, Maria's supportive role intensified. She encouraged Tsubasa during distractions following alchemist attacks, leading to joint performances. When Tsubasa became emotionally overwhelmed by a seal from Millaarc and harsh criticism, Maria intervened with a deliberate slap that broke the seal and shocked Tsubasa from despair, demonstrating her willingness to confront hard truths for her allies. Her resolve in battle was evident as she wielded Airgetlám against threats like the Noble Red alchemists and Custodian-related enemies. Her core drive persisted: to protect the world and loved ones, atone for her past, and uphold Serena's legacy.

Physically, Maria possesses cyan eyes and long pink hair, typically styled with two horn-like curls secured by blue flower accessories atop her head, the rest flowing loosely to her hips. Her attire evolved from an early white corset with navy jacket and shorts to a XV ensemble featuring a salmon and lavender overcoat, striped top, white miniskirt, and high-heeled boots.