O-Parts Hunter, known as 666 Satan (Japanese: 666 ～サタン～, Hepburn: Roku-Roku-Roku Satan) in Japan, is a Japanese manga series written and illustrated by Seishi Kishimoto. It was originally published by Enix, who later became Square Enix, in their Monthly Shōnen Gangan magazine from August 2001 to December 2007, with the chapters collected into 19 tankōbon volumes. The series draws heavily from Kabbalistic traditions and Abrahamic demonology for its plot, and less so on Japanese folklore. 666 Satan has been released internationally in Spain, France, Italy and North America, although, Viz Media changed the title to O-Parts Hunter in the latter. Source: Wikipedia (en)