21st Century Boys: The Perfect Edition, Vol. 1

This is the story of a group of boys who try to save the world. The war is over. The Friend is dead. Finally free from the threat of extinction, peace has come to the people of Tokyo once again. But the mystery surrounding the Friend still remains. Nobody knows who the Friend was or where he came from, and the only clue is hidden deep in the Kenji's memories. The time has come to open Pandora's box and see what was left behind.

21st Century Boys: The Perfect Edition, Volume 1, by Naoki Urasawa.