Code Geass: Lelouch of the Re;surrection

Two years after the death of Lelouch VI Britannia, his sister Nunnally vi Britannia and her bodyguard Zero are in the middle of a goodwill visit to a desert nation. Unfortunately, they are soon attacked by a squad of mecha. While Zero attempts to protect Nunnally in his own giant robot, he finds himself outmaneuvered and defeated before the battle can even begin, resulting in the two being kidnapped by their attackers.

Suspecting that the Kingdom of Zilkhistan—a land known for producing some of the world's best mercenaries and strongest warriors—is behind the kidnapping, Kallen, Sayoko, and Lloyd find themselves on the run. However, at this moment they have an unexpected reunion with enigmatic immortal C.C., who is currently traveling to investigate a set of ancient ruins like those she and Lelouch visited off the coast of Japan. But soon, this group of frenemies begins to realize that their problems might be more related than they appear at first glance.