O-Parts Hunter, known as 666 Satan (666 ～サタン～ Roku-Roku-Roku Satan?) in Japan, is a Japanese manga series published by Enix, and later Square Enix under its Monthly Shōnen Gangan imprint, and created by Seishi Kishimoto, whom later released the manga Blazer Drive. 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.
Set in near future, it tells the story of Ruby, an ordinary girl, who became a treasure hunter after her life is changed dramatically when her father, who was also a treasure hunter, dies. Her objective is to find O-Parts: magical items hidden in ruins which grant people superhuman powers and can only be used by an O.P.T. (O-Part Tactician), Angel, or Devil. She soon meets a mysterious boy named Jio Freed who, due to having a dark, lonely past, seeks to conquer the world. Jio is hostile to her at first, but ends up traveling with Ruby as her bodyguard. When Ruby is attacked by an O.P.T., who claims to be Satan, Jio rushes to her rescue and a battle occurs. Initially they are on the losing side, but Jio releases his true power and is revealed to be not only an O.P.T., but the real Satan. Thus, the two continue to travel together in hopes of unlocking their pasts.
O-Parts, named after out-of-place artifacts (OOParts), are ancient relics found throughout the world of O-Parts Hunter, primarily used as weapons or forms of transportation. The people who are able to use O-Parts are known as O.P.T. (O-Part Tacticians), who are able to release their "spirit energy" and focus it into the O-Part, which it then absorbs and uses as fuel to activate a special effect or ability, usually of a fantastic nature.
Angels and Demons
Throughout the entire O-Parts Hunter universe, there are creatures named after angels and demons that are sealed within humans with amazing powers, all of which are being searched for by the Stea Republic (angels) and the Zenom Organization (demons) in order to awaken what is assumed to be a weapon within a Kabbalah and a reverse Kabbalah that are found on the North and South Pole respectively.
As of the beginning of the time-skip all but four Angels have yet to be inserted into the Kabbalah, those four being Metatron, Zadkiel, Samuel, and Sandalphon.
Story arc 1 starts from issue 1 to 24
Story arc 2 starts from 25 to 53 (aka Rock Bird Event)
Story arc 3 goes from 54 to 76
A. E. Sparrow of IGN titled the header for his review of the series as "Naruto is in its blood." This may refer to the fact that the creators of O-Parts Hunter and Naruto are twin brothers. Sparrow said that one reads the series when "you feel you've outgrown Naruto and want to find something with a bit more to it."