Nunnally vi Britannia is a royal princess born to the Emperor of Britannia, Charles Di Britannia, and Marianne Vi Britannia. She was 87th in line of succession to the Britannia Throne before she and her brother were exiled to Japan as political prisoners. She is Lelouch’s younger sister who is wheelchair-bound due to old bullet wounds on her legs, and blind due to psychological trauma while witnessing the brutal murder of her mother, Marianne Vi Britannia. Lelouch believes that she may be able to see again someday. After the confrontation of Lelouch with the Emperor of Britannia about the murder of their mother, both Lelouch and Nunnally were sent to Japan as political trade. They then went on to live in Kururugi Residence where she first met Suzaku Kururugi.
After Britannia invades Japan, Lelouch hides their identity in fear of their safety and changes their surname to Lamperouge. They then seek help from Marianne’s old allies, the Ashford family, who kept their identity a secret and allows the two siblings to live in a building on campus to accommodate her disabilities. Nunnally attends Ashford Academy’s middle school and is friends with Lelouch’s classmates, particularly with Shirley. She is very kindhearted and calls the Elevens “Japanese people.”
She is also the reason why Lelouch wants to revolt against Britannia. Lelouch wants to build a better world for Nunnally. In episode 24, despite the fact that the The Black Knights were on the verge of winning, Lelouch abandons them to rescue Nunnally after learning of her being kidnapped by V.V.
In the beginning of R2, it seems that nobody at Ashford Academy remembers her existence; everyone apparently recognizes that Lelouch has a younger brother, Rolo, instead of Nunnally. After recovering his memory, Lelouch deduces that Nunnally is likely being held hostage by the Emperor, who would not hesitate to use his children to achieve his goals. As a result, Lelouch must try to maintain the masquerade that he has not regained his memories in order to protect her.
Nunnally makes her first appearances in episode 5 of R2, revealing that she still recalls who Lelouch is, addressing him as her older brother, and shocks Lelouch with the revelation that she has been assigned to become the new Governor-General of Area 11.
Nunnally discloses her own decision to become Governor of Area 11. Much to the shock of Lelouch, she decides to continue her late sister Princess Euphemia’s will by reinstating the Special Administrative Region in Japan, sharing her and Suzaku’s belief that the world can be changed in gentle ways. Currently, however, Nunnally has yet to know of the true identity of Zero and the existence of the Geass, but she heard Lelouch’s voice when the ship exploded alluding to the possibility that she does. Her Imperial Name and status was also restored.