HGUniversal Century

RGM-79U GM SLOEP

A GM that never got its war, finally getting its kit.

MechaGrade Score

3.7/5

GM SLOEP · 1/144 · 2025

GradeHG

Scale1/144

Released2025

Runnersn/a

Check price on Amazon

Affiliate link. We may earn a commission at no extra cost to you.As an Amazon Associate we earn from qualifying purchases.

The verdict

This is a base HG GM body carrying an entirely original, purpose-built Aqua Pack, and that backpack is the whole reason to buy it.

I went in expecting a reskin and came out impressed that Bandai tooled a wire-deployed pod, rotating hydrofoils, and removable leg ballasts for a mobile suit whose entire combat history is two paragraphs long. It is not a technical showcase like an RG, but as a gimmick kit built around one accessory system, it delivers more than its obscure source material has any right to.

Best for: UC completionists and MSV-R readers who want the obscure amphibious GM variant nobody else is making, plus anyone who likes a kit built around one clever mechanical gimmick

The full review

What it is

The GM Sloep is a standard HGUC-line GM frame wearing a completely new aquatic loadout: an Aqua Pack backpack, a sonar gun, and a pair of auxiliary ballast tanks bolted to the legs. What got me is that none of that is decoration. The pack's hydrofoils actually rotate and extend, the pod detaches and pays out on an included wire like it is really being launched underwater, and the leg ballasts pop off individually if you want the suit in a stripped-down loadout. For a Premium Bandai release of a mobile suit that appeared in a photonovel that never even got a Western release, the amount of dedicated tooling here is honestly more than I expected.

The catch

The suit underneath the gear is a plain GM, so if you already own an HGUC GM or GM variant, you are paying a premium mostly for the backpack. At 3,520 yen (around 24 USD) it costs more than a standard HG for what is still a fairly simple, blocky silhouette once the Aqua Pack comes off. It is Premium Bandai only, so there is no wide retail stock and no guarantee of a rerun, and the wire-deploy pod is a fun party trick the first few times but is more a display pose than something you will fidget with during normal play.

Who it's for

Grab this one if you collect UC-era GM variants, like a kit that centers on one genuinely engineered gimmick, or just want the obscure aquatic GM that MSV-R fans have wanted in plastic for years. Skip it if you are chasing a great pure sculpt or top-tier articulation for the money, since the base body is a standard-issue GM and the price bump is entirely about the backpack. If the Aqua Pack does not interest you, a regular HGUC GM will get you a very similar suit for less.

The build story

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

The build itself is standard HG-era GM: straightforward part fit, no inner frame to speak of, and cleanup is easy since the runners are simple. The backpack subassembly is where the actual attention went, with the pod, hinge points for the hydrofoils, and the wire spool needing a little more care during assembly than the rest of the kit combined.

Color separation follows typical HGUC GM conventions, molded in its main colors with some sticker work expected for the finer sonar gun and pack details. The real payoff is the accessory set: sonar gun, detachable Aqua Pack, rotating hydrofoils, wire-deploy pod, and separately removable leg ballasts, which is a lot of distinct parts and play patterns for an HG built around a suit that barely appears in canon.

Lore & trivia

01The GM Sloep was the Earth Federation's first mass-produced amphibious mobile suit, developed as an answer to Zeon's underwater MS after the Federation had no real countermeasure of its own.
02The project was rolled into the RAG-79 Aqua GM before it saw real deployment, and the existing GM Sloep units were converted back into standard GMs, leaving only two as data-collection testbeds that were later dismantled.
03The suit's debut material, the photonovel Mobile Suit Gundam MSV-R: The Troublemakers, has never been officially released in the West, making this HG one of the more obscure MSV-R kits Bandai has tooled.
04The kit is a Premium Bandai exclusive that shipped in October 2025 for 3,520 yen (about 24 USD), with an entirely original Aqua Pack mold rather than a repurposed part from another GM kit.