O-Parts Hunter Review: A Boy with a Demon Inside Him Seeks the Legendary OPT in a Post-Apocalyptic World
by Seishi Kishimoto
*Affiliate link — I earn a small commission at no extra cost to you.
Quick Take
- Seishi Kishimoto's (Masashi Kishimoto's twin brother) action manga with the post-apocalyptic relic-hunting premise — the demonic possession element gives the protagonist a consistent tension between ambition and loss of control
- The O-Parts system — ancient relics that interact with user ability — provides clear combat framework
- 19 volumes complete; substantial complete post-apocalyptic action manga
Who Is This Manga For?
- Readers who want post-apocalyptic action manga with demonic possession elements
- Anyone interested in the sibling dynamic between the Kishimoto brothers' work
- Fans of relic-hunting adventure with escalating ability combat
- Readers looking for complete action manga in the 19-volume range
Content Warnings & Age Rating
Age Rating: T+ (Older Teen) Content Warnings: Post-apocalyptic violence; demonic possession and its consequences; dark themes including Jio's background; battle content with real stakes
T+ rating — action content appropriate for older teens.
Yu's Rating
| Category | Score |
|---|---|
| Story Depth | ★★★☆☆ |
| Art Style | ★★★☆☆ |
| Character Development | ★★★☆☆ |
| Accessibility for Non-Japanese Readers | ★★★★☆ |
| Reread Value | ★★★☆☆ |
Story Overview
The world of O-Parts Hunter is a post-apocalyptic landscape where ancient relics called O-Parts — objects with inexplicable power — are sought by OPTs (O-Parts Tacticians), people with the ability to activate them. The relics range from small enhanced tools to legendary items of world-altering significance.
Jio Freed's stated goal is to rule the world. This is a child's ambition stated with full seriousness. Inside him lives Satan — a demonic entity that takes over when Jio's life is genuinely at risk, with consequences Jio cannot control.
Ruby is an OPT hunter who travels with Jio. Their search for legendary O-Parts intersects with a larger conflict — organizations competing for relics capable of reshaping the world — and with the question of what Satan actually is and what it means for Jio.
Characters
Jio Freed — A protagonist with a world-ruler ambition that is both comedy and serious — the series takes his goal at face value and asks what kind of person makes that claim; the demon inside him complicates every answer.
Ruby — The OPT hunter partner whose relic expertise and practical capability provide the team's professional competence.
Satan — The demonic entity within Jio whose nature and relationship to the post-apocalyptic world's origin is the series' long-game mystery.
Art Style
Seishi Kishimoto's art has the clear action-manga lineage visible in his brother's work — character designs functional enough for battle clarity, action choreography with good spatial coherence. The post-apocalyptic world design uses the expected wasteland aesthetics competently.
Cultural Context
O-Parts Hunter ran in Monthly Shonen Gangan from 2001 to 2007. The series was published in VIZ's American market as O-Parts Hunter, though the Japanese title is 666 Satan — the biblical 666 reference is intentional to the demonic possession premise. Seishi Kishimoto's career has been significantly overshadowed by his twin brother's, which is a real shame given the series' genuine quality.
What I Love About It
The demon-in-the-boy concept is not metaphorical. When Satan takes over Jio, something genuinely different inhabits his body, with its own goals and its own history that the series reveals across the 19 volumes. The relationship between Jio's ambition and Satan's actual nature is the series' best long-game narrative element.
What English-Speaking Fans Say
Western readers describe O-Parts Hunter as an underappreciated complete action series — specifically noted for the post-apocalyptic world having genuine scope, for the Satan possession mythology being more developed than expected, and for the full 19-volume arc having satisfying resolution. Often recommended alongside the author's twin's work for comparison.
Memorable Scene ⚠️ Spoiler Warning
The revelation of what Satan actually is — and its connection to the post-apocalyptic world's origin — reframes the entire premise in a way that makes the long-game worth the commitment.
Similar Manga
- Naruto — Same era shonen action with similar protagonist arc structure (by Seishi's twin)
- Rave Master — Post-world-cataclysm relic-hunting adventure
- Flame of Recca — Demon-adjacent powers in action manga
- Blue Exorcist — Demonic inheritance shaping protagonist's life
Reading Order / Where to Start
Volume 1 — Jio and Ruby's meeting, the O-Parts world, and the first demonstration of Satan establish the premise and the tone.
Official English Translation Status
VIZ Media published the complete English series. All 19 volumes available.
Pros & Cons
Pros
- Satan mythology developed across full 19 volumes
- Post-apocalyptic world has genuine scope
- Complete with satisfying resolution
- Underrated work by a skilled creator
Cons
- Overshadowed by more famous contemporary action series
- Art is functional but not distinctive
- Mid-series pacing uneven
Format Comparison
| Format | Notes |
|---|---|
| Individual Volumes | VIZ Media; complete series |
| Digital | Available |
Where to Buy
Get O-Parts Hunter Vol. 1 on Amazon →
This post contains affiliate links. If you purchase through these links, I may earn a small commission at no extra cost to you. As an Amazon Associate, I earn from qualifying purchases.
*Affiliate link — I earn a small commission at no extra cost to you.
Written by
Yu
Manga Enthusiast from Japan
I grew up in Japan and manga literally saved me during a tough time in elementary school. My English isn't perfect, but my love for manga is real — and I want to share it with you.
Disclosure: This post contains affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you.