Big Comic Spirits
Written and illustrated by Naoki Urasawa, while also writing "Monster", 20th Century Boys was originally serialized in "Big Comic Spirits" from 1999 to 2006. The 249 individual chapters were published into 22 tankōbon volumes by Shogakukan from January 29, 2000 to November 30, 2006. A sequel, titled "21st Century Boys", started in "Big Comic Spirits"s January 19, 2007 issue and ran until July. The 16 chapters were released into 2 volumes on May 30, 2007 and September 28, 2007. A one-shot manga titled "Aozora Chu-Ihō" ("Blue Sky Advisory — Kiss") was published in the February 2009 issue of "Big Comic Spirits", it was credited to "Ujiko-Ujio", the pen-name of the fictional manga creator duo Kaneko and Ujiki in "20th Century Boys". There are also 2 spinoff manga based on "20th Century Boys", not translated into English.