Nina Tucker is the young daughter of Shou Tucker, the Sewing-Life Alchemist, who resides in an eastern border city of Amestris. She is four years old in the 2003 anime adaptation and five in the original manga and the 2009 anime Fullmetal Alchemist: Brotherhood. She has blue eyes and long brown hair that she wears in braids reaching her waist. Nina is a cheerful, playful, and excitable child who is almost always seen with her large pet dog, Alexander, whom she loves deeply. She is also very loving toward her father and never stops believing in him, despite his neglectful behavior.

Her central role in the story begins when Edward and Alphonse Elric come to her father’s home to learn about his bio-alchemical research. Nina quickly bonds with the brothers, referring to Edward as “little-big brother” and Alphonse as “big-big brother” in the 2003 anime, and simply as “Big Brother” to both in the manga and Brotherhood. She confides in them that her mother left the family two years earlier, which has made her lonely because her father has become increasingly immersed in his work. The Elrics, who also grew up without a father figure, sympathize with her and spend much of their time playing with her and Alexander.

As Shou Tucker’s annual state alchemist evaluation approaches and he faces losing his certification, he grows desperate. Despite Nina’s attempts to comfort him, he uses the same forbidden alchemical method he used on his wife to transmute Nina and Alexander into a single speaking chimera. When the Elrics return and discover this, Edward is horrified and attacks Tucker, but the chimera—still retaining some of Nina’s consciousness—pleads for her father’s life. Unable to reverse the transmutation, the brothers report Tucker to the military, and the Tuckers are placed under house arrest. Shortly afterward, the Ishvalan vigilante known as Scar arrives, kills Shou Tucker, and then ends the chimera’s life in an act of mercy, recognizing that its existence is one of suffering.

Nina’s death leaves a profound emotional scar on both Edward and Alphonse. Edward is haunted by guilt and nightmares, and the incident reinforces his determination to use alchemy for good and to oppose those who abuse it. In the 2003 anime, a later storyline involves Shou Tucker surviving and using a Philosopher’s Stone to attempt to revive Nina as a distorted chimera homunculus, but this version of Nina never speaks and her nature remains ambiguous. In both adaptations, Nina’s fate serves as a critical turning point that deepens the series’ exploration of the ethical limits of alchemy, the value of human life, and the consequences of unchecked ambition. She has no alchemical abilities herself; her significance lies entirely in her innocence and the brutal demonstration of how that innocence can be destroyed by those who prioritize power and status over humanity.