G-Shock has spent 43 years as the poster child for digital timekeeping, so we think it’s safe to say that a square case with no LCD in sight is uncharted territory for the brand. Yet that’s exactly what Casio cooked up here, reinterpreting the original 1983 DW-5000C as a pure three-hander. The watch community caught wind through leaks weeks ago, promptly lost its collective mind, and slapped a nickname on the thing before Casio could even finish the reveal. Say hello to the G-Shock 2500 Series, better known around the internet as the “CasioNaut.”
A Nickname Casio Didn’t Ask For
If that moniker sounds familiar, it should. Back in 2019, the octagonal GA-2100 earned the “CasiOak” nickname for its Royal Oak-adjacent profile and ballooned into one of the biggest hits in the brand’s modern catalog.
This time around, the 2500’s softly rounded case flanks have enthusiasts drawing a straight line to Gérald Genta’s other icon, the Patek Philippe Nautilus. Casio, for its part, insists the design simply carries the “functional beauty” of the original square into gentler contours. Either way, lightning looks ready to strike twice.
A Date Window With a Side Hustle
The most clever bit of the new 5757 module lives at 3 o’clock. Casio calls it Multi-Mission Date. It’s a three-cell wheel that shows the date during normal timekeeping, but then rotates into stopwatch duty. The setup lets you count elapsed minutes while the small seconds hand at 9 o’clock ticks off the seconds.
That same wheel also handles setup for a full auto-calendar programmed clean through 2099.
Hands That Roll With the Punches
Hands are usually the first casualty when an analog watch meets impact, so Casio attaches the minute hand magnetically instead of press-fitting it to the shaft. Take a hard knock and the hand gives with the impact, then works its way back into position within a few minutes.
Beyond that, you get 200 meters of water resistance, a seconds hand you can park to stretch battery life, and nine launch variants. Those span featherweight 47-gram resin models all the way up to the 138-gram GMC-2500D, with its steel bezel, bracelet, and sunray brass dial.
Spec Sheet
Model: G-Shock 2500 Series (GAC-2500 / GMC-2500 / GMC-2500D)
Case Size: 46.7 x 43.8 x 12.9mm (GMC) / 46.7 x 44.5 x 12.7mm (GAC)
Case Material: Resin and bio-based resin; stainless steel bezel (GMC)
Movement: Casio Module 5757 quartz (±15 seconds per month)
Functions: Multi-Mission Date, 30-minute stopwatch, full auto-calendar to 2099, LED light
Water Resistance: 200m
Crystal: Mineral glass
Band: Bio-based resin or stainless steel bracelet
Weight: 47g (GAC) to 138g (GMC-2500D)
Battery Life: Approx. 2 years (CR1025)
Pricing & Availability
The 2500 Series lands this November, and the barrier to entry is wonderfully low. The all-resin GAC-2500 models start at $145, the steel-bezel GMC-2500 trio runs $280 to $300, and the bracelet-equipped GMC-2500D tops the range at $350. Head over to G-Shock’s website to pick your poison.
Recap
G-Shock 2500 Series “CasioNaut”
G-Shock reinterprets its original 1983 square as a fully analog watch, complete with a shape-shifting date window and a nickname borrowed from Patek.
