Maria is a second-generation Neogene created by Tatsuoki Furumizu using his genetic code combined with that of first-generation Neogenes, with Reina providing the genetic material that makes her the biological mother. As a result of the accelerated growth process typical of the Neogenes, Maria appears much older than her actual age; she is in fact younger than Rihoko. She is first seen in combat training alongside her other second-generation sisters, demonstrating considerable strength and skill that later leads to her being chosen as the wielder of the Dual Cloneblade, a replica of the true Witchblade. Her designated nickname as a Cloneblade wielder is Lady.

Maria's personality initially blends a childlike obsession with stuffed animals and a ruthless combat ability. She loves dolls and plush toys but consistently ends up destroying them, using them as a tool to relieve stress. During training, she defeats multiple opponents without feeling any guilt. As she struggles to understand her own existence, she lives a troubled life trying to figure out what her purpose is. She is sarcastic, cynical, and not afraid to speak her mind, yet she often questions for what or whom she is acting and what she truly wants, which frequently earns scolding from her handlers.

Her motivations center on a desperate search for identity and belonging. After learning that Reina is her genetic mother, Maria seeks maternal affection, but Reina rejects her, revealing that she never had any real maternal feelings for Maria nor even truly knew of her existence. In a rage, Maria kills Reina. Following this act, her personality undergoes a drastic change: she becomes almost catatonic, losing her previous childishness and selfishness. She also alters her appearance, dyeing her originally three-colored hair a single black color to resemble the mother she killed.

Maria serves as the primary antagonist in the final quarter of the anime series. Her role evolves from an antagonist trained by the NSWF to a broken figure driven by the loss of the maternal bond she never truly had. Her key relationships include Reina as her mother and creator, Tatsuoki Furumizu as her genetic designer, and her fellow second-generation Neogene sisters. Her development is marked by a tragic arc from a confused, violent child seeking purpose to a hollow, catatonic being after destroying the one person she hoped would give her meaning.

Notable abilities include enhanced physical combat skills, the power and weaponry granted by the Dual Cloneblade, and the accelerated aging that is characteristic of all Neogenes. Her rapid physical maturation and emotional instability make her a volatile and formidable opponent.