This timepiece is a magnificent artifact from June 1969, as confirmed by the serial number 90600100. The reference ALDS 2901-Y is defined by its substantial stainless steel case and a breathtaking charcoal grey dial that radiates a serious, professional aura. It is powered by the sophisticated Caliber 9812, a 21-jewel manual-wind movement featuring a dedicated mechanical alarm—a marvel of micro-engineering that uses a tiny internal hammer to strike a pin, creating a crisp, buzzing "chirp" that was the pinnacle of wearable tech for the era.

The architecture is quintessentially functional, utilizing a dual-crown system: the 2 o'clock crown sets and winds the alarm, while the 4 o'clock crown manages the time. The dial is a work of technical brilliance, featuring a central "alarm hand" tipped with a distinctive arrow and a inner-rotating chapter ring for precise alarm setting. Flipping the watch over reveals the crisp caseback engraving with the Parawater designation and the serial number 90600100, definitively confirming its authentic Japanese Domestic Market (JDM) heritage. This is an essential acquisition for an elite collector who appreciates complex mechanical complications, the soul of a vibrating alarm heart, and the bold, purposeful presence of a vintage Citizen.