HGBuild Divers

Mercuone Unit

An underwater armor set that only makes sense once you already own the suit it's built to dress up.

MechaGrade Score

3.2/5

Mercuone Unit · 1/144 · 2020

GradeHG

Scale1/144

Released2020

Runnersn/a

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The verdict

I like this kit for exactly one reason and it is not the box art.

The Mercuone Unit is armor, not a mobile suit, and once I understood that going in, it stopped disappointing me. On its own it is a handful of fins and shell plating that looks unfinished. Paired with a Core Gundam and the separate Mercuone Weapons set, it turns into a genuinely cool submarine-styled Gundam. Buy the parts, not the promise on the box.

Best for: Build Divers completionists who already own a Core Gundam kit and want the full underwater Planet Armor look

The full review

What it is

The Mercuone Unit is one of the Planet Armor support kits from Gundam Build Divers Re:RISE, built to snap onto any HGBD:R Core Gundam (the ones that shipped inside Earthree Gundam, Venustwo, or Marsfour) and turn it into Hiroto's underwater specialist, the Mercuone Gundam. Opening the box, what you get is the shell armor and most of the frame for that ocean-diving silhouette, all those fins running down the limbs and back that are supposed to help it cut through water. Clipping it onto a Core frame is quick and satisfying, and the moment the fin arrangement clicks into place I got why Hiroto picked this configuration for a deep-sea mission in the show.

The catch

Here is the part nobody puts on the front of the box: this set does not include the backpack or the weapons, those live in a separate Mercuone Weapons kit you have to buy on top of this one, and without either of those extras the Mercuone looks unfinished, more like a stripped fish than a suit. It also does not come with its own Core Gundam frame, so if you don't already own one of the compatible HGBD:R kits, this box does nothing for you. Builders online also point out how close the silhouette reads to the Earthree armor, the two share enough of the same design language that from a few feet away they're easy to mix up.

Who it's for

This is not a first kit and it is not a standalone kit, full stop. If you're new to Gunpla or want one box that gives you a complete mobile suit, skip this and grab any core HGBD:R Gundam or a mainline HG instead. But if you've already got a Core Gundam sitting around and you're chasing the full underwater Planet Armor look from Re:RISE, or you're a Build Divers completionist working through all eight armors, this earns its spot on the shelf once you pair it with the Weapons set. Go in knowing it's a component, not a kit, and it delivers.

The build story

What the build is actually like, and the engineering worth knowing about.

Assembly is standard HG-level plastic model work, runners to clip, gates to clean up, a handful of stickers for markings. Nothing about the build itself is fiddly or frustrating, the fin pieces snap on securely and the shell plating fits the Core frame without any looseness. It's a short, relaxed build, closer to an accessory project than a full afternoon kit.

The real engineering payoff is how the fin arrangement reshapes a generic Core Gundam into something with actual character, that thin, aquatic profile is convincing once everything is on. Articulation is whatever your donor Core frame allows since this kit contributes armor rather than joints, so it does not restrict posing much beyond adding a bit of bulk to the limbs and back.

Lore & trivia

01The Mercuone Gundam is a custom Gunpla piloted by Hiroto Kuga in Gundam Build Divers Re:RISE, built specifically for underwater operations.
02It is one of eight Planet Armor configurations introduced in the series, each built to snap onto a shared Core Gundam frame for a different combat role.
03The kit released in Japan in February 2020, with the companion Mercuone Weapons set following in March 2020 to complete the loadout.
04The design leans on an extensive array of body fins to sell its water-mobility concept, giving it a look distinct from the more conventional Gundam frames it shares parts compatibility with.