King Seiko Hi-Beat Automatic Ref. 5621-7021 – July 1973 – freshly serviced

Serviced in Japan (in January 2026) · Original KS Crown · Classic Stainless Steel Case

This King Seiko Hi-Beat Automatic Reference 5621-7021 from July 1973 is one of the technically and historically most significant late King Seiko models. It hails from the final phase of the classic King Seiko line, combining high-frequency precision, automatic winding, and a clearly defined, period-typical case design of the early 1970s.

The watch was fully disassembled and professionally serviced in Japan in January 2026. Accordingly, it is in excellent technical and optical condition. It is equipped with an original King Seiko crown with KS logo and a new black leather strap.

Caliber 5621A – Hi-Beat Technology at Grand Seiko Level

Inside, the Seiko Caliber 5621A operates, an automatic Hi-Beat movement with 28,800 vibrations per hour. This movement belongs to the renowned 56xx caliber family, which Seiko used in the early 1970s in both King Seiko and – in a slightly modified form – in Grand Seiko (Cal. 564x).

The Caliber 5621A is characterized by:

• automatic winding unit
• high oscillation frequency (28,800 A/h)
• hacking seconds
• very stable timekeeping with regular maintenance

and is considered by collectors to be the pinnacle of industrial Japanese precision mechanics before the quartz era.

Regarding specific Reference 5621-7021

The reference 5621-7021 stands for a striking stainless steel case variant with clear edges and precisely defined flanks, which differs significantly from earlier, softer King Seiko cases. This design reflects the objective-functional style of the early 1970s and gives the watch a timeless, elegant presence on the wrist.

Within the King Seiko hierarchy, the 5621-7021 was:

• technically clearly positioned above the older 44xx and 45xx hand-wound models,
• on par with contemporary Grand Seiko automatic models,
• but designed to be somewhat sportier and more suitable for everyday wear.

It is precisely this combination of Hi-Beat automatic, modern case design, and classic King Seiko DNA that makes the reference 5621-7021 particularly collectible today.

Condition

Overall, the watch is in a very well-maintained, consistent condition. The case, dial, and hand set show only slight, age-appropriate signs of wear that emphasize the authentic character of the watch. Minimal crack in the watch glass just above 12 o'clock.
The movement starts cleanly after servicing.

Technical Specifications

• Brand: Seiko
• Model Line: King Seiko
• Reference: 5621-7021
• Year of Manufacture: July 1973
• Movement: Automatic, Seiko Caliber 5621A
• Frequency: 28,800 A/h (Hi-Beat)
• Hacking Seconds: Yes
• Case Material: Stainless Steel
• Diameter: 36.6 mm (without crown)
• Height: 10.2 mm
• Lug-to-Lug: 41.5 mm
• Lug Width: 18 mm
• Weight: approx. 49 g (incl. new leather strap)
• Crown: Original King Seiko crown with KS logo
• Strap: New black leather strap

Warranty (used)
This is a used item. The limitation period for claims for defects (statutory warranty) is 12 months from delivery.

Note
As this is a used watch, water resistance cannot be guaranteed. To protect the movement, the watch should not come into contact with water or moisture.