This timepiece is a magnificent artifact from August 1974, as confirmed by the serial number 483668. The reference 2021-5180 is defined by its regal gold-toned rectangular case and a breathtaking champagne sunray dial that radiates a warm, sophisticated glow. It is powered by the highly reliable Caliber 2021, a precision two-hand quartz movement engineered during the dawn of the quartz revolution to provide uncompromising accuracy in an ultra-slim profile that sits with effortless grace on the wrist.

The architecture is quintessentially classic, utilizing sharp, polished baton indices and a minimalist handset that prioritizes clean, uncluttered lines. The dial is further distinguished by the iconic "Daini Seikosha" lightning bolt logo above the 6 o'clock position, signifying its heritage from Seiko's legendary second factory. Flipping the watch over reveals the crisp stainless steel caseback with the BASE METAL / ST. STEEL BACK designation and the serial number 483668, definitively confirming its authentic Japanese Domestic Market (JDM) heritage. This is an essential acquisition for a connoisseur who appreciates early high-end quartz history, the mechanical soul of a precision heart, and the timeless, understated class of the vintage Seiko Tank line.