Seiko Spirit Roman Dial  5P31-6A50 from February 1987, as confirmed by the serial number 728506. As a vintage watch and horology expert, I can tell you the Spirit line was a cornerstone of Seiko's refined Japanese Domestic Market (JDM) offerings, providing exceptional accuracy and durability for the everyday professional. It houses the reliable Caliber 5P31, a high-grade quartz movement designed with Anti-Magnetic 60G protection, ensuring precision even in the increasingly tech-heavy environments of the late 80s.

The architecture is quintessentially classic, utilizing a slim, round case with a gold-toned bezel that frames an elegant cream dial adorned with crisp Roman numeral indices. The bi-color integrated bracelet provides a sophisticated presence on the wrist, while the 10 Bar (100m) water resistance makes this a rare dress-style watch with true daily-wear capability. Flipping the watch over reveals the iconic "Double Wave" medallion style engraving, definitively confirming its status as a robust, professional-grade instrument from Seiko's golden era of quartz.