The Empire of Brittania has invaded Japan using giant robot weapons called Knightmare Frames. Japan is now referred to as Area 11, and its people the 11s. A Brittanian who was living in Japan at the time, Lelouch, vowed to his Japanese friend Suzaku that he'd destroy Brittania. Years later, Lelouch is in high school, but regularly skips out of school to go play chess and gamble on himself. One day, he stumbles on terrorists 11s who've stolen a military secret and is caught by a member of the Brittanian task force sent after them, who is Suzaku. As the rest of the squad arrives, Suzaku is shot for disobeying orders, while the military secret, a young girl, gives Lelouch the power to make anyone obey any order. He takes command of the terrorists and leads them to crush the approaching Brittanian force. However, Suzaku is secretly made the pilot of Brittania's brand new test model Knightmare, Lancelot. Lelouch becomes the masked king Zero to lead the rebellion to defeat Brittania. This series follows Suzaku's side of the story, while Lelouch of the Rebellion follow's Lelouch's.

An alternate Code Geass story in which Lelouch's fate is unknown after his meeting with C.C., whether he be dead or alive. Nunnally makes a Geass contract and gains the power to read the lines of the future. She also obtains a new body and takes up piloting an unusual Knightmare Frame.

The Empire of Britannia invaded Japan using giant robot weapons called Knightmare Frames. Japan was reduced to Area 11, an imperial colony, and its people referred to as the Elevens. At the time, Lelouch, a young Britannian boy exiled to Japan, vowed to his Japanese friend Suzaku that he would destroy Britannia. Years later, Lelouch is a high school student who regularly skips school to play chess and gamble. When he stumbles on a terrorist group of Elevens who are caught by a Britannian task force after stealing a military secret, Lelouch is unexpectedly reunited with Suzaku, who works as a member of the Britannian military. As the rest of the task force arrives, Suzaku is shot for disobeying orders, while the military secret, a young girl, gives Lelouch the power to make anyone obey any order. Taking command of the terrorists, Lelouch adopts the alias "Zero" and begins his rebellion to crush Britannia once and for all. However, his greatest friend soon becomes one of his most troubling enemies when Suzaku becomes the pilot of Britannia's new test model Knightmare, the Lancelot. Note: Storyline is a bit different than the anime.