Code Geass: Lelouch of the Rebellion

Britannia's conquest of Japan in 2010 is over in a month, thanks to walking war machines called Knightmare Frames, and the country becomes Area 11. Lelouch — an exiled prince of the empire that did the conquering — is living in Tokyo under a fake name, watching the war from a school desk and waiting for his moment. The moment arrives in the form of C.C., a green-haired girl who gives him a power called Geass: an absolute one-time order any human will obey. Lelouch decides to use it to burn Britannia from the inside, and the show becomes the chess match he plays against his own empire.