TV-Series
Description
Euphemia li Britannia is the Third Princess of the Holy Britannian Empire and a central figure in the first season of the series. She is the third daughter of Emperor Charles zi Britannia and the biological younger sister of Cornelia li Britannia, as well as the half-sister of Lelouch Lamperouge and Nunnally Lamperouge. She is sixteen years old with long pink hair typically styled with two buns, violet eyes, and is often seen wearing a pink and white dress.

Unlike many of her siblings, Euphemia possesses a kind-hearted, open-minded, and highly optimistic personality. She despises conflict and is one of the few members of the Britannian royalty who does not hold racist views towards the Japanese people, known as Elevens. Her universal respect for others stems from her childhood experiences, particularly her close relationship with Lelouch and Nunnally, and her belief that problems should be solved through understanding rather than force.

Euphemia arrives in Area 11 to serve as the Sub-Viceroy alongside her sister Cornelia. Her primary motivation is to bridge the gap between Britannia and its subjected peoples, seeking to end the cycle of violence and discrimination. She wishes to create a world where people can smile without fear, a goal she shares with Suzaku Kururugi. She demonstrates high-level deductive reasoning skills, being the first person to deduce that the masked revolutionary Zero is actually her exiled half-brother, Lelouch, a secret she promises to protect.

In the story, Euphemia takes a pacifist approach to governance. She appoints Suzaku Kururugi as her personal knight, and a deep romantic bond develops between them. Her most significant action is the proposal of the Special Administrative Zone of Japan, a plan to grant the Japanese people limited autonomy and equal rights. This proposal is a direct attempt to provide a safe haven for Lelouch and Nunnally. However, during the ceremony for the Special Zone, a tragic accident occurs when Lelouch's Geass power activates uncontrollably, giving her the involuntary command to "kill all the Japanese." Trapped in this state, she begins a massacre, forcing Lelouch to fatally shoot her to stop the violence.

In her final moments, she briefly fights off the Geass with her willpower, dying in Suzaku's arms without realizing the horror she had been forced to commit. Following this event, the Britannian government officially declared her mentally incompetent and stripped her of her royal status, and she is infamously remembered by the public as the "Massacre Princess". Her death becomes a pivotal tragedy that drives the motivations of several characters in the second season, including Suzaku’s thirst for revenge and Nunnally’s attempt to revive her peaceful ideals.

Regarding abilities, while she despises combat, Euphemia is capable of piloting Knightmare Frames. Her greatest strengths lie in her interpersonal perception, creative problem-solving, and an unwavering idealism that rivaled even Lelouch's strategic mind.