What episode did Anya from Code Geass first appear?

Anya Alstreim, also known as "Euphemia Li Britannia," first appears in Episode 2 of Code Geass, titled "Knight of the Round Table."

She is introduced as the younger sister of Clovis la Britannia, the Viceroy of Area 11 (Japan), and is presented as a friendly and benevolent figure, much to the surprise of Lelouch Lamperouge and his sister Nunnally.