Code Geass: Hangyaku no Lelouch

Beginning with the conquest of Japan, the Holy Empire of Britain established itself as a powerful military nation in 2010. After its quick defeat, Japan was renamed Area 11, and in an effort to regain its independence, it encountered strong opposition from these despots.
Unfortunately, Lelouch Lamperouge, a British student, is caught in the crossfire between the rebel armed forces of Area 11 and the Britannian military. Fortunately, a mysterious girl named C.C. shows up just in time to give him Geass, the “Power of Kings.” Understanding the enormous potential of his newly discovered “power of absolute obedience,” Lelouch sets out on a treacherous quest as Zero, the masked vigilante, leading a vicious assault against Britannia in an attempt to exact final retribution.