Lelouch is killed by the Black Knights after being revealed and mysteriously ends up in the Soul Society where he becomes and rises up as a Shinigami of the Gotei 13.
The end of the Second Battle in the Tokyo Settlement left Lelouch feel despair when it's assumed that his sister Nunnally as well as their maid Sayoko died in the blast of the FLEIA warhead. Things only got worse for Lelouch in the Ikaruga when Schneizel revealed his identity and his Geass power to the core members of the Black Knights which leads to them going against him.
The Black Knights succeeded in killing Lelouch and with it, Lelouch dies figuring that his life was over. But by the actions of a Shinigami named Kajiro Sumeragi, Lelouch ends up in the Soul Society, residing in the eighth district of East Rukongai known as Raku’uta. It is there he unexpectedly gets reunited with his half sister Euphemia li Britannia as well as Shirley Fenette.
One year later, after a Hollow attack, Lelouch and Euphemia enroll in the Shin’o Academy to train and become Shinigami of the Gotei 13 and in the process, they are met with people, most of them that Lelouch knew before. In time, Lelouch as well as Euphie and Shirley gain friends and allies as well as dangerous enemies.