The Empire of Britannia has invaded Japan using giant robot weapons called Knightmare Frames. Japan is now referred to as Area 11, and its people the 11's. A Britannian who was living in Japan at the time, Lelouch, vowed to his Japanese friend Suzaku that he'd destroy Britannia. 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 11's who've stolen a military secret and is caught by a member of the Britannian 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 of Geass, which makes anyone obey any order. While Suzaku is secretly made the pilot of Britannia's brand new prototype Knightmare, Lancelot, Lelouch becomes the masked Zero to lead the rebellion to destroy Britannia once and for all.
Lelouch Lamperouge
The title character and protagonist of the show, Lelouch Lamperouge is seemingly an ordinary 17-year-old student at the Ashford Academy. In reality, he is the son of the Emperor of Britannia and the late Empress Marianne. His real name is Lelouch vi Britannia, the Eleventh Prince of the Britannian Empire prior to his mother's assassination. When he gets caught up in a battle between the military and Japanese rebels, he gains the power of Geass, which forces others to obey his orders without question. With this power, he begins his quest to destroy Britannia under the alias of Zero.
Suzaku Kururugi
Lelouch's childhood friend and son of Japan's last prime minister, Suzaku is in the service of the Britannia Army as a soldier, and was chosen to test an experiment new model of Knightmare Frame, the Lancelot. Suzaku believes achieving results by wrong or illegal methods is meaningless and does not approve of Zero's actions.
C.C.
A mysterious green-haired girl who bestows the power of Geass upon Lelouch under the condition that he grant her greatest wish. C.C.'s abilities caught the interest of Britannia and she was imprisoned as a part of Britannia's experiments in the past. She passively oversees Lelouch's missions to ensure that he does not die and to help his plans succeed.
Nunnally Lamperouge
Nunnally is Lelouch's younger sister, who is wheelchair-bound due to bullet wounds on her legs, as well as blind due to psychological trauma from witnessing the brutal assassination of her mother.
Kallen Kōzuki
Kallen is a Britannian-Eleven girl who believes herself to be a Japanese person at heart and prefers to be known by her birth name. Her father is Britannian and her mother is an Eleven; her father comes from a prestigious Britannian family and as such she attends the Ashford Academy, where she is a member of its student council and is one of its most outstanding students. Though she maintains a frail-girl image at school, she is a member of a Japanese resistance cell.
Knightmare Frames
Knightmare Frames ('Knightmare' is a play on "nightmare" and a knight's mare, referring to the weapon itself; frame is the civilian word for bipedal machines in general) are robotic combat machines intended as a replacement for main battle tanks and other conventional land warfare vehicles. The bulk of Knightmare Frame models are produced by the Britannian Empire, who pioneered the design. As the series progresses, Japan, India, and other countries develop their own Knightmare Frames to match Britannia's advantage.
