Code Geass: Hangyaku no Lelouch R2

Synopsis

The final battle for the Damocles rages on between 2 separate major fronts: Lelouch confronting Nunnally for the Damocles key and Suzaku and Kallen engaging in one final showdown. In the midst of the fighting, all the series' still-surviving characters give their final thoughts on their reasons for participating in the conflict. The final battle concludes with Kallen seemingly killing Suzaku, but at the same time, Lelouch managed to acquire the Damocles key from Nunnally using his Geass. Broadcasing to the entire world, Lelouch declares that now that he controls the FLEIJA weapons, he now stands in absolute control of the world.

Two months later, Lelouch leads a convoy to execute those who rebelled against him before being stopped by what appears to be Zero. Swiftly going past Lelouch's bodyguards, Zero then stabs him using the sword Lelouch himself once carried. The Zero stabbing Lelouch is revealed to be Suzaku, who faked his own death, and as it turns out, the entirety of the series' final battles was all part of Lelouch's final plan: the Zero Requiem. With the world's hatred now solely focused on Lelouch, Suzaku, as Zero would then execute him, allowing humanity to finally enter a peaceful future while remaining as Zero to help it along.

In fulfilling this plan, Suzaku and Lelouch would be establishing peace and simultaneously imposing the greatest punishments on themselves: death for Lelouch who wishes for a tomorrow with his sister, life for Suzaku who wishes to atone for his sins through death. With only a few select people knowing the truth, Lelouch dies, having succeeded in destroying and rebuilding the world. With Lelouch's death, the world improves significantly as the people act together for the sake of the future. The series ends with C.C. musing to herself how Geass condemns people to solitude, but in Lelouch's case, this was wrong, happily noting how he overcame his loneliness.

(Source: Code Geass Wiki)