Nina Wáng is a central character in the anime My-Otome. She is introduced as the top-ranked Coral student at Garderobe Academy, a position she maintains through diligent study and rigorous training. Her homeland is the Grand Duchy of Artai, a relatively poor nation that lacks its own Meister Otome, and she is determined to become one in order to serve her country and, above all, to earn the affection and pride of her adoptive father, Sergay Wáng, a high-ranking military officer in Artai's service. Nina's early life was marked by hardship; she was found by Sergay as an infant during a violent raid on an underground settlement, and he took her in, giving her the birthday of the day they met. This deep-seated desire for Sergay's love is the primary emotional driver behind her ambition and many of her actions.

Nina is serious, disciplined, and hard‑working, and she holds herself to the highest standards. This contrasts sharply with the carefree and inexperienced Arika Yumemiya, who enters Garderobe as a special student. From their first meeting, Nina is irritated by Arika's lack of sophistication and her seemingly effortless connections, especially when Arika begins to develop a close friendship with Sergay. Nina's feelings toward Arika are a mixture of jealousy, resentment, and grudging respect; they become rivals and, at times, friends, with a complicated bond that deepens over the course of the story. Nina also shares a room with the shy Erstin Ho, who harbors romantic feelings for her, a dynamic that adds emotional weight to their friendship.

As the narrative progresses, Nina's drive to become a Meister Otome is exploited by the ambitious Duke Nagi Dai Artai. After a series of events that deepen her jealousy against Arika—including seeing a handmade handkerchief from Arika in Sergay's possession—Nina forms a contract with Nagi using the corrupted Meister GEM known as the Ultimate Black Diamond, which is a twisted version of the founder Fumi Himeno's Pure White Diamond. In this role, Nina becomes a powerful foe, wielding a pair of daggers or sai that can combine into a large sword, and an ultimate attack called the Sword of Miroku. Her role as Nagi's Otome brings her into direct conflict with Arika, culminating in a battle that leads to Erstin's death and leaves both girls deeply scarred. Later, it is revealed that Nina is actually the biological daughter of Sifr Fran, the former queen of Windbloom, making her the rightful heir to the Windbloom throne—a secret that adds another layer to her identity.

After her defeat, Nina withdraws from public life and tends to the comatose Sergay in a secluded cabin. When he eventually awakens with no memory, she introduces herself as a woman, indicating a desire to start a new relationship with him as an adult rather than as a daughter. In the sequel OVA My-Otome Zwei, Nina is drawn back into action. She aids Nao in exploring ancient ruins, where she discovers a new Meister GEM, the Neptune Emerald. With this GEM, she materializes a new robe and wields a bident, using an attack called Dash Cold Water Spout. She also gains the ability to travel to the Black Valley, where she meets other characters. Throughout her journey, Nina's character develops from a single‑minded, love‑driven girl into a more mature individual who must balance her personal desires with the responsibilities of her heritage and her abilities. Her notable abilities as an Otome include exceptional combat skill, the use of multiple GEMs and associated weapons, and a hidden royal lineage that makes her a key figure in the world's politics.