Tennis player Kei Nishikori spotted wearing a Casio

At the Tokyo 2020 Olympic Games, Japanese tennis star Kei Nishikori took to the hard courts wearing a watch that had already sold out months before the Opening Ceremony. Spotted during his first-round match — competing in Japan's traditional red — Nishikori's wrist carried the IFL Watches x The Dial Artist 'Crystal Jellyfish' limited-edition Casio G-Shock GA-2100, one of just 200 pieces produced globally. For a resin sports watch retailing under $750, the cultural moment it generated was remarkable.

The GA-2100 platform, nicknamed 'CasiOak' by the collector community for its unmistakable octagonal bezel that draws aesthetic comparisons to the Royal Oak, debuted in 2019 and immediately disrupted the affordable watch space. Its carbon core guard structure keeps the case an extraordinary 11.8mm thin — slimmer than many dress watches — while retaining Casio's full suite of G-Shock durability: 200-metre water resistance, shock protection, and the brand's reliable analog-digital movement with world time, stopwatch, and five daily alarms. The 'Crystal Jellyfish' treatment replaces the standard opaque resin with a fully transparent skeleton case and band, while The Dial Artist applied multicolour indices — pink, green, yellow, blue — against a glitter-infused black dial, with rainbow typography across the bezel ring.

Collector significance for this reference is outsized relative to its price point. The 200-piece limitation, combined with IFL Watches' strong UK-based community reach and The Dial Artist's reputation for meticulous hand customisation, meant the drop sold through almost instantly. Secondary market prices climbed sharply post-release, with verified sales trading at multiples of retail — a phenomenon more commonly associated with Swiss independents than Casio collaborations.

Nishikori, a former US Open finalist and long-time ambassador for Japanese sporting culture, wearing this piece at the Olympics rather than a luxury Swiss sponsor watch speaks to a generational shift in how elite athletes relate to horology. The choice feels authentic rather than contractual.

At a list price of approximately $713 (£519), the Crystal Jellyfish sits at the intersection of streetwear culture, watch collecting, and Olympic sport — a combination that guarantees its place in G-Shock lore regardless of its modest origins.