From MangaHelpers:

All humans in this world can use the power of the light of mana, and those who can't are considered to be subhuman 'Norma.' The world is like a peaceful utopia, and the celebrated princess Angelize leads a happy life. She believes that the only darkness left in the world is the existence of the horrible Norma.

However, in a ceremony on her 16th birthday, the truth is revealed--Princess Angelize is a Norma. Now she is going to learn what her society does to Norma. She is sent to an isolated island full of others like her, who are taught that the only reason they are allowed to live is in order to fight to protect the peace of this world. Now "Ange" is part of a squad that pilots Paramails and fights invading extradimensional dragons.

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.

A side-story centered on the school idol Saki Rukino, and tells her story from both past and present points of view.

SEVEN-O agents’ work is all about controlling illegal operations related to a drug called Anthem. They operete under the “double decker system”, and this how the veteran Doug Billingham and the novice Kirill Vrubel ended up working together.