Code Geass: Lelouch of the Rebellion: Season 2, Episode 3

2 - 3: Turn 03 - Imprisoned in Campus

Lelouch tries to get clues about Nunnally's whereabouts, but no one around him remembers her. To find her, he'll have to figure out his mysterious new brother, Rolo. But he'll have to do it while maintaining the guise that his memory hasn't returned.