666 Satan (666～サタン～, Roku Roku Roku Satan), also know in US as O-Parts Hunter, is a Japanese manga series published by Square Enix under its Monthly Shōnen Gangan imprint, and created by Seishi Kishimoto, the younger twin brother of Masashi Kishimoto, creator of the manga series Naruto. The series draws heavily on Kabbalistic traditions and Judeo-Christian demonology for its plot, and less so on Japanese folklore. It is licensed for an English language release by Viz Media, which released it under the title to O-Parts Hunter.