O-Parts Hunter

O-Parts Hunter, more commonly known as 666 Satan (666 ～サタン～, Roku-Roku-Roku Satan?), 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 2001 and 2007, and later collected into 19 tankōbon volumes. The series draws heavily from Kabbalistic traditions and Judeo-Christian demonology for its plot, and less so on Japanese folklore. It was released in English by Viz Media, who released it under the title O-Parts Hunter.