Citizen Tsuyosa Automatic vs Casio G-Shock GA-B2100 CasiOak
Citizen's timepiece meets Casio's diver
Quick Verdict
The Casio G-Shock GA-B2100 CasiOak (~$144) delivers Casio Quartz (Solar-Powered) technology at $188 less than the Citizen Tsuyosa Automatic (~$332). The Tsuyosa Automatic justifies its premium with Made in Japan heritage and Automatic Caliber 8210. Both represent excellent choices in the luxury watch category.
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Specifications Compared
| Feature | Citizen Tsuyosa Automatic | Casio G-Shock GA-B2100 CasiOak |
|---|---|---|
| Price | ~$332 | ~$144 |
| Case Size | 40mm | 44.4mm |
| Movement | Automatic Caliber 8210 | Quartz Module 5611 (Tough Solar + Bluetooth) |
| Caliber Type | Citizen/Miyota In-House Automatic | Casio Quartz (Solar-Powered) |
| Power Reserve | 40 Hours | — |
| Water Resistance | 50m (5 ATM) | 200m (20 ATM) |
| Crystal | Sapphire Crystal with Cyclops | Mineral Glass |
| Case Material | Stainless Steel | Carbon Core Guard Resin |
| Origin | Made in Japan | Made in Japan |
Category-by-Category Analysis
Design & Aesthetics
Citizen's design language vs Casio's approach
Movement & Performance
Automatic Caliber 8210 vs Quartz Module 5611 (Tough Solar + Bluetooth)
Wearability & Fit
40mm vs 44.4mm — different wrist presence
Value & Cost of Ownership
Casio is $188 more affordable
Water Resistance
50m (5 ATM) vs 200m (20 ATM)
Materials Face-Off
| Component | Citizen Tsuyosa Automatic | Casio G-Shock GA-B2100 CasiOak |
|---|---|---|
| Case alloy | Stainless steel 316L. | Casio's proprietary monocoque case technology integrating carbon fibers into fine resin. The carbon fibers dramatically raise the tensile strength and modulus of elasticity of the case structure, allowing the GA-2100 to achieve an 11.8mm thickness — the thinnest analog G-Shock at launch — while maintaining full 10m drop impact resistance. Total case weight: 51g. |
| Sapphire crystal | Verneuil-grown synthetic corundum, Mohs 9. Anti-reflective coating, single side. Mohs 9 | Flat mineral glass with Mohs hardness ~6. Thermally tempered for impact resistance — flexes under force rather than shattering like sapphire. Not scratch-proof, but replacement crystals cost ~$10. |
| Lume specification | Super-LumiNova grade C1 or BGW9 (variant dependent). Glow duration relatively short — Citizen's lume application on the Tsuyosa is modest by Seiko st | Durable urethane polymer resistant to sweat, saltwater, UV radiation, and skin oils. Features quick-release spring bars. Known to last 5–10 years with daily wear before degradation. |
| Bracelet alloy | Stainless steel 316L matching the case. | Secured by 4 Phillips screws for 200m (20 ATM) water resistance. Houses two SR726W silver-oxide button cell batteries accessible for user replacement. |
| Premium Lineage: Cobarion® & DAT55G Titanium (MRG-B2100) | — | The luxury MRG-B2100 variant ($3,500+), hand-assembled at Yamagata Casio's Premium Production Line (PPL) by certified "Medalist" craftsmen, uses Cobarion® (cobalt-chromium alloy, 4× harder than pure titanium) bezels and DAT55G titanium (3× harder than pure titanium) bracelet links. |
Cost of Ownership Compared
The Casio G-Shock GA-B2100 CasiOak saves you $518 over 5 years of ownership
Who Should Pick Which
Pick the Citizen Tsuyosa Automatic if…
- Budget-conscious buyers wanting serious quality under $500
- Those who prioritize scratch resistance — sapphire crystal
Pick the Casio G-Shock GA-B2100 CasiOak if…
- Anyone wanting an indestructible daily beater under $100 with serious design credibility
- Water sports enthusiasts — 200m WR with G-Shock shockproofing
- Watch modding enthusiasts — massive aftermarket ecosystem of metal conversion kits
- High-end collectors needing a dedicated beater alongside their luxury pieces
Citizen Tsuyosa Automatic
- No hacking seconds. When you pull the crown to set the time, the seconds hand continues running. Setting precisely to-the-second is impossible. The single most-cited Tsuyosa complaint.
- Unidirectional rotor. Only winds in one direction; reserves take longer to build than bidirectional movements.
- Modest accuracy spec. ±10 to +25 sec/day in practice is the realistic band; significantly worse than the Tissot Powermatic 80.
- Proprietary endlinks. Limited strap-swap options.
Casio G-Shock GA-B2100 CasiOak
- Stealth-black legibility deficit: The GA2100-1A1 has absolutely no Neobrite luminescent paint on hands or indices. Low-light readability is poor — you must rely entirely on the Double LED Super Illuminator.
- Mineral glass scratches: Not sapphire. Daily beater use will accumulate minor scuffs over time. Replacement crystals are cheap (~$10) but require caseback removal.
- Tiny digital subdisplay: The LCD window at 4:30 is small and genuinely difficult to read for anyone with less than perfect vision. The Hand-Shift feature (sweeps hands to 7:35 position to clear the LCD) helps but isn't a substitute for a full digital display.
- Module 5611 is quartz: For mechanical-watch purists, this is a non-starter. For everyone else, it's a feature — better accuracy (±15 sec/month), no winding, no expensive servicing, and 3-year battery life.
Our Verdict
Citizen
Tsuyosa Automatic
Choose the Citizen Tsuyosa Automatic if you prioritize Citizen/Miyota In-House Automatic engineering, Made in Japan craftsmanship, and 50m (5 ATM) water resistance. At ~$332, it delivers Automatic Caliber 8210 with 40 Hours power reserve.
Check Price on AmazonCasio
G-Shock GA-B2100 CasiOak
Choose the Casio G-Shock GA-B2100 CasiOak if you value Casio Quartz (Solar-Powered) technology, Made in Japan heritage, and 44.4mm proportions. At ~$144, the Quartz Module 5611 (Tough Solar + Bluetooth) with ample power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Citizen Tsuyosa Automatic and Casio G-Shock GA-B2100 CasiOak represent two distinct approaches to fine watchmaking — the Citizen bringing Made in Japan tradition while Casio delivers Made in Japan engineering.