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.
Himari Takakura passes away after going out on a trip with her brothers, twins Kanba and Shōma. She was, however, miraculously saved by a spirit in a penguin-shaped hat. In return for her extended life, the twins must search for an item known as the Penguin Drum with the aid of three penguins, which are visible only to the siblings.