Code Geass: Lelouch of the Rebellion

August 10th in the year 2010 of the Imperial Calendar, The Empire of Britannia declared war upon Japan.
Decimating Japan with their overwhelming military power, Japan was stripped of its freedom, rights and even its name. Now known only as Area 11, and its people Elevens. Lelouch Lamperouge, a Britannian high school student who regularly skips class to gamble, finds himself thrust into the crossfire between a band of rebels and the military. Stumbling upon a mysterious girl named C.C., she grants him Geass, the "Power of Kings". Now taking the mantle of the masked terrorist Zero, Lelouch is forced to fight against his longtime friend Suzaku in order to bring about change in Britannia.

Note: The storyline of this manga is slightly altered from the anime. Notably, Knightmare Frames are omitted entirely.