20th Century Boys is a Japanese manga series written and illustrated by Naoki Urasawa. It was serialized in Big Comic Spirits from 1999 to 2006 and has been collected into 22 volumes. The story follows a group of childhood friends who must band together to stop a mysterious cult known as "Friend" from enacting a catastrophic plan that threatens the entire world. The series has been praised for its complex storytelling, well-developed characters, and thought-provoking themes. It has also been adapted into a live-action film and a novel.