20th Century Boys is a Japanese manga series written and illustrated by Naoki Urasawa. It was originally serialized in Shogakukan's seinen manga magazine Big Comic Spirits from 1999 to 2006, with the 249 chapters published into 22 tankōbon volumes. A 16 chapter continuation, titled 21st Century Boys, ran in the same magazine from 2006 to 2007 and was gathered into two tankōbon volumes. It tells the story of Kenji Endo and his friends, who notice that a cult-leader known only as "Friend" is out to destroy the world, and that his cult icon bears a striking resemblance to a symbol developed during their childhoods. The series makes many references to a number of manga and anime from the 1960s–1970s, as well as to classic rock music, its title being taken from T. Rex's song "20th Century Boy".