An immortal, mysterious girl who controls the power of Geass.
Actually, in the past, she was a slave who ran away from her master. She was then rescued by a nun, who can be considered the previous "C.C.," and was given a Geass power that C.C. used to make her loved by everyone. However, that was the trick the nun used to force C.C. to inherit immortality. And so, C.C., who had the power to control Geass and immortality, known as the "Code," lived for many years.
She arrives at the Temple of Twilight to save Lelouch from the Emperor of Britannia, and also to fulfill her wish to die. But she changes her mind after hearing Lelouch's words.
During her escape from this dimension, she loses her immortality and memories as C.C.
Later, she regains her memories with the help of Marianne, who had been inside of Anya.
After she sees her allies, Charles and Marianne, meet their end at Kamine Island, C.C. decides to stand by Lelouch, who is about to walk a new path of blood.