Nina Einstein is introduced as a bookish member of the student council at Ashford Academy. Nina demonstrates an acute
xenophobic reaction to Elevens and is initially intimidated by Suzaku when he arrives in the school. She develops an obsessive
crush on the Third Princess Euphemia after the latter helps her during a traumatizing hostage incident at the Lake Kawaguchi
Convention Center Hotel. She subsequently comes to rely on Euphemia for emotional support.
Lloyd Asplund is interested in Nina's personal research regarding the possibility of using Uranium-235 as a fuel, even
providing her with some sakuradite to further her research. Following Euphemia's death, Nina becomes emotionally and mentally
unstable. In a misguided attempt to kill Zero and avenge the princess, she arms the Ashford's Ganymede Knightmare Frame with a
prototype nuclear reactor, intending to detonate it and take out all of Tokyo. It fails to explode, however.
Nina is eventually recruited by Second Prince Schneizel as chief of his "In Vogue" research team headquartered in Dallas, Texas.
Schneizel seems to keep her stable by reminding her of how Euphemia would act, though her bitterness towards Zero is not forgotten.
Under him, she eventually creates a working bomb. The bomb, codenamed F.L.E.I.A. (Field Limitary Effective Implosion Armament,
pronounced "Freya"), vaporizes everything within a specific radius. The one used on Tokyo obliterates everything within eight kilometers,
while another used on the Britannian capital of Pendragon destroys everything within 100 kilometers, accomplished by removing the limiter
on the device. Though she is initially thrilled to see her revenge on Zero coming true, Nina is actually shocked and devastated by the
destruction caused by her weapon, which causes more than 35 million casualties when fired on Tokyo Settlement. Lloyd tells her that
she'll have to become detached if she intends to continue being a scientist.
Nina is forced to go into hiding shortly thereafter, as several countries, Britannia included, are searching for her in connection
with the development of F.L.E.I.J.A. Lelouch enlists her aid in creating a countermeasure to F.L.E.I.J.A., which she successfully
completes. She offers to assist him in deploying it, but he refuses to let her, considering it his task for killing Euphemia. Nina
then admits that she will likely never forgive Zero for that, but needed to find her own answer, to which Lelouch responds by
calling her a good person. She is later seen as a prisoner of Emperor Lelouch, along with the rest of the Black Knights and several
Lelouch supporters, though she's not slated for execution. She's also seen in the picture of Viletta and Ohgi's wedding, having
apparently gotten over her xenophobia.