Sentinel

Twelve employees building transforming robots and refining a thousand details

At a glance

Status: Active. Output remains steady.
Based in: Taito in Tokyo in Japan.
Known for: RIOBOT; METAMOR FORCE; Fighting Armor; transforming robot figures with metal components.
Good fit: collectors who enjoy mechanical transformation; Brave series robots; Marvel heroes reimagined as armored machines.
Before buying: preorder a priority release when possible; limited production can make METAMOR FORCE and Fighting Armor difficult to find later.
Research coverage: Solid

TL;DR

A roughly 12-person independent Tokyo studio (est. 2009) specializing in premium mecha and action figures with die-cast components.
METAMOR-FORCE line features fully transforming Brave series figures; RIOBOT covers broader mecha licenses with premium articulation.
Prices range from roughly $33 for 4Inch-Nel to $200-$270+ for METAMOR-FORCE; limited runs mean pre-ordering is strongly recommended.

Twelve People Building Transforming Robots

千値練. A thousand values, refined. That is what the kanji in Sentinel's Japanese name reads (千 sen, thousand; 値 chi, value; 練 neru, to refine), and it doubles as a mission statement. Ono Tadaichi established the company in July 2009 in Taito-ku, Tokyo, the same ward that houses Akihabara's northern edge and Ueno's cultural district. He built Sentinel as a figure planning and production management firm with an unusually specific mission: creating premium robot and action figures with ambitious engineering for specialized series that larger manufacturers often could not justify.

The tagline on their corporate site translates to 'a thousand values are built up,' the idea that great products emerge from the careful refinement of countless small details. The English name 'Sentinel' was chosen partly as a phonetic bridge and partly for its connotation of a vigilant guardian, which suits their mecha-heavy catalog. The team stays small by design: approximately 12 employees handle product planning and prototype development in-house, contracting manufacturing to Chinese factories.

METAMOR-FORCE, RIOBOT, and Fighting Armor

Sentinel's catalog centers on premium robot and action figures with metal components and mechanical transformations. Its flagship lines serve different buyers. METAMOR-FORCE is the headliner, offering fully transforming robots based primarily on Brave series titles such as GaoGaiGar and Dagwon. These figures transform through built-in mechanical sequences rather than swapped parts, with engineering that recalls high-end model kits more than mass-market toys.

RIOBOT covers a broader range of robot series, including Gurren Lagann, Voltron, and Getter Robo, with each release engineered for a wide range of motion and satisfying metal weight. The line has earned a strong reputation among robot fans. RE:EDIT focuses on larger figures, while SV-Action offers highly poseable characters from games and anime.

Fighting Armor represents one of Sentinel's boldest creative choices: a Marvel-licensed line that reimagines Iron Man, War Machine, Captain America, and other Western superheroes as mecha-styled armored figures. It's a thoroughly Japanese interpretation of Western IP, treating superhero suits as engineering problems, all joints and armor plating. The line has found an audience among both mecha collectors and Marvel fans who appreciate the fresh perspective.

4Inch-Nel was Sentinel's entry into the deformed action figure space, offering poseable chibi-style figures of characters from Mega Man, Kirby, and other game franchises at around four inches tall. The line demonstrated Sentinel's range beyond pure mecha, though mecha and tokusatsu properties remain the company's heartland.

Pre-Order or Miss Out

Sentinel figures span a wide price range. 4Inch-Nel deformed figures sit at the budget end around ¥5,000-8,000 ($33-53 USD), while RIOBOT releases range from ¥10,000-20,000 ($67-133 USD). METAMOR-FORCE and premium releases can reach ¥30,000-40,000+ ($200-270+ USD), reflecting the die-cast materials and transformation engineering involved.

Pre-ordering is strongly recommended for Sentinel releases. Limited production runs mean that popular figures, especially METAMOR-FORCE entries and Fighting Armor Marvel releases, can become difficult to find at retail after release. AmiAmi, HLJ, and other major Japanese retailers carry Sentinel products, but stock moves quickly.

For mecha enthusiasts, Sentinel fills a specific and valuable niche. If you grew up watching Brave series anime, very few other manufacturers are producing transforming die-cast figures of these properties at this quality level. For Marvel collectors, Fighting Armor offers a distinctly different take from the Revoltech, Figuarts, or MAFEX versions of the same characters. If you want a figure you can actually transform and pose with satisfying ratchet clicks, Sentinel is where to look.

The Brave Series Stronghold

The mecha collectible market has grown more competitive with Bandai’s METAL BUILD line, Threezero’s ROBO-DOU, and various Chinese manufacturers entering the space. Sentinel’s Brave series catalog remains unusual for pairing these licenses with die-cast transformation, and over 520 items on MyFigureCollection since 2009 show what a small focused team can accumulate. Fighting Armor gives Marvel characters a distinctly Japanese mecha interpretation unlike the approaches taken by Revoltech, Figuarts, or MAFEX.