Euphemia li Britannia
Euphemia li Britannia is Lelouch’s half-sister and the Third Princess of the Britannian Imperial Family; she is the sibling Lelouch cares most about after Nunnally. She is a kindhearted and open-minded woman who despises conflict in any form.
Euphemia joins her older sister Cornelia in governing Area 11, becoming the Sub-Vicereine. She develops a relationship with Suzaku Kururugi, whose views reflect her own, and eventually appoints him as her personal Knight.
She loves Suzaku Kururugi and declares her love to him in episode 20.
Towards the end of the first season, she announces her intent to form the Special Administrative Zone of Japan in the region under Mount Fuji, giving the Japanese people their name and country back. During the administration changeover ceremony, she falls under the accidental influence of Lelouch’s Geass and is compelled to kill the Japanese people. She is shot by Zero to stop the ensuing chaos and dies from her injuries, sparking the Black Rebellion. In supplementary materials, it is revealed that Britannia officially declared Euphemia responsible for the massacre and that she had been deprived of royal status and executed by the Britannian Army following the rebellion. She comes to be known as the “Massacre Princess” to the general public.