Everything that has ever lived will eventually die. That's the only thing that stays constant in the world Lelouch lives in, a world where giant, man-eating monsters known as Titans freely roam the earth. To some, this fact can be depressing. But to him, it serves as his inspiration. Because he knows that the same rule can be applied to the Titans.

After being defeated in his fight against Arima, Kaneki blacks out and wakes up in the world of Remnant...

As a result of the Zero Requiem, Lelouch has been killed and sent to another world by the Collective Unconscious. There, he finds two worlds that are completely different from his own. One being present in what he knows to be reality and the other being present in a video game called: Sword Art Online, and funnily enough, he just so happens to own a copy.