The "CasioNaut": Everything we know about the G-Shock GAC-2500 and GMC-2500

Casio put nine unreleased watches on its own Japanese website, then took them down. The internet had already screenshotted everything.

That was the first week of September. The models in question are the GAC-2500 and GMC-2500 — a new all-analog G-Shock family with a rounded, eared case that a lot of people looked at once and said Nautilus. The nickname stuck within a day: CasioNaut.

None of this is official. Casio has said nothing. But the listing came from Casio’s own servers, not a rumour account, which makes it about as reliable as a leak gets.

What actually leaked

Nine references across three versions, all expected in November 2026:

GAC-2500 — full resin, 47g, ¥20,900. Four colours: black, olive green, white, yellow.
GMC-2500 — steel bezel on a resin band, 68g, ¥37,400 (¥39,600 for the gold IP). Silver-on-black, silver-on-white, gold IP.
GMC-2500D — steel bezel on a full steel bracelet, 138g, ¥49,500. Black dial or blue dial.

“Steel on Steel” banner — the two GMC-2500D bracelet models, black and blue.

“Steel on Resin” banner — the two GMC-2500 strap models, black and silver dial.

Case size is 46.7 × 44.5 × 12.7mm in resin, 46.7 × 43.8 × 12.9mm in metal. Big on paper, but that’s a G-Shock number — the 47g resin version will wear lighter than anything in your box.

The part worth noticing: this is the first time G-Shock has launched a line in resin and metal-clad versions at the same time. Usually you wait two years for the metal one. Here you get to choose on day one, from cheap to properly expensive.

What’s inside it

Module 5757, and it’s fully analog — no digital window, which is the real break from the CasiOak. Hands, a 0–60 subdial doing seconds duty, and a date at three.

Stopwatch, 1-second increments, 30-minute range
Second-hand sleep — park the seconds hand and battery life goes from about 2 years to about 5
Hand shift, plus hand-and-day alignment correction after a knock or a magnet
LED light, 1.5-second burst
CR1025 cell
The dials in the leaked renders read WATER RESIST 20BAR — 200m, standard G-Shock

It’s a simple module. That’s not a criticism at ¥20,900 — it’s how the price gets there.

GMC-2500D blue dial, straight-on product shot. Caption: “0–60 subdial doing seconds duty, date at three, no digital window anywhere. That’s the real break from the CasiOak.”

Homage, or a bit close?

Here’s the thing people keep missing. The GA-2100 earned “CasiOak” because it echoed the Royal Oak. The Royal Oak and the Nautilus were drawn by the same man — Gérald Genta, 1976 for the Nautilus. So Casio isn’t wandering into a new neighbourhood. It’s walking down the same street it’s been on since 2019.

Look at the bezel properly, though. The eight facets, the G-SHOCK at twelve and PROTECTION at six — that’s the 5000-series square, rounded off. It’s closer to a DW-5600 that went to the gym than to anything Swiss.

Whether that’s affectionate homage or a copy is exactly the argument that’ll run in every watch group for the next two months. We have opinions. We’ll keep them until we’ve handled one.

MC-2500D black dial, straight-on. Caption: “Cover the logo. What do you see first — a G-Shock, or something else?” — this one is bait, and it should be.

What this means in Bangladesh

Don’t do the yen conversion and get excited. ¥20,900 is roughly $134, and you will not pay $134 for this in Dhaka.

Remember what happened with the GA-2100: a cheap watch on paper that spent two years selling for whatever the seller felt like asking, because nobody could keep stock. Expect the same pattern here, and expect the first units to arrive through grey channels well before any authorised stock shows up. Expect fakes by December, too — an octagonal resin G-Shock is the easiest thing in the world to counterfeit badly.

Our advice, for now: wait for the resin. The GAC-2500 at ¥20,900 is the interesting one. The steel bracelet version at ¥49,500 puts you in the same money as a real Seiko automatic, and that’s a different conversation entirely.

GMC-2500 black dial on the black resin strap. Caption: “The sensible middle. Steel where you see it, resin where it touches you — which matters in May.”

Your turn — we actually want to know

This is a rumour post, so the comments matter more than usual.

Resin or steel? The 47g GAC-2500, or the 138g GMC-2500D on the bracelet?
Which colour? Olive green is the one we keep coming back to. Yellow will divide this group completely.
Homage or copy? Say it plainly. We’ll publish the best answers.
What would you actually pay for one landed in Dhaka?

Drop your answer in the group, or message us on Messenger. When these officially launch in November, we’ll do a proper breakdown — and if we can get hands on one, a real review.

Everything above comes from a listing Casio published and removed. Specs and prices are Japanese MSRP and can change before launch. We’ll update this post the moment Casio confirms anything.

Sources

G-Central — Casio leaks upcoming G-Shock GAC-2500 and GMC-2500 “CasioNaut” watches, module 5757 functions revealed — the original report (7 September 2026), and the source of the nine-model lineup, Japanese pricing, dimensions and module 5757 spec.
Gear Patrol — G-Shock’s new “CasiOak” successor is an affordable, all-analog Nautilus lookalike — the USD conversion, the November window, and Casio’s own attribution to its 5000 series.
Esquire UK — Casio’s Nautilus — you sent this one; it wouldn’t load for me, so nothing above draws on it. Worth a read before publishing.