Code Geass: Hangyaku No Lelouch LOST COLORS

A mysterious young man stumbles onto the grounds of Ashford Academy and encounters members of the Student Council before collapsing. After being asleep for several days, he awakens and is met by the entire Student Council. This young man, named Rai, suffers from amnesia. He has a Geass ability similar to Lelouch's, but is activated by voice.