The case design features the thin bezel and simple shape typical of the era, but to visually express the alarm function—Japan’s first at the time—it achieves a unique look with its distinctive crown placement and the indicator disc hand at the center of the dial. The upper surface of the lugs is edged with two differently angled planes, making them appear slimmer than they actually are. The back edge of the lugs is chamfered for comfort against the skin.
The case design is a simple shape with a thin bezel, which was the mainstream at the time.
The back edge of the lugs is chamfered for comfort against the skin. The upper surface of the lugs is edged with two differently angled planes, making them appear slimmer than they actually are.
The early models used a "double case back" structure to resonate the alarm sound, with sound holes in the outer case back to let the sound from the inner resonating case back ring out clearly.
The case features two slightly oversized 5.5mm crowns—one at 2 o’clock for the alarm and one at 4 o’clock for time adjustment—improving operability and serving as the model’s most distinctive design feature.
A circular alarm time indicator disc is placed at the center of the dial, and by rotating the entire disc, it greatly enhances usability and makes the alarm setting easy to understand at a glance.
The second hand is straight, and the hour and minute hands are diamond-shaped—a very basic combination—but the long second and minute hands are curved at the tips to avoid interference with the box glass.