The title character and protagonist of the show, Lelouch Lamperouge is a seemingly ordinary 17-year-old student at Ashford Academy. In reality, he is Lelouch vi Britannia, the exiled son of the Emperor of Britannia and the late Empress Marianne, forced to flee to Japan after his mother's assassination. When he gets caught up in a battle between the military and Japanese rebels, he gains the power of Geass, from a mysterious girl named C.C. allowing him to force others to obey his orders without question, and begins a quest to utilize this power to destroy Britannia under the alias of Zero.

He then joined the remaining people of Japan and became their leader. Later on, he made it public to the whole of Britannia and renamed Area 11 into United States of Japan and created a group of japanese named 'The Black Knights'. He became the leader of the black knights and negotiated with Lakshata, a genius in creating military weapons. He also found out that his school mate, Karen Kouzuki, was a half britannian and half japanese. Karen joined the black knights and became Lelouch's knight. And Lelouch's code name was Zero. Meaning to say, Lelouch Lamperouge a.k.a Lelouch vi Britannia is Zero. Therefore, Zero goes into war with Britannia and even negotiated with the biggest japanese gangster.