Seiko Lord Matic 5606-7000 – Caliber 5606A, 23 jewels, Suwa Seikosha – monocoque case – October 1969 – freshly serviced

The case back features an instruction that is quite rare to find on watches: OPEN THRU GLASS.

This watch cannot be opened from the back. The case back is not a lid, but rather part of the case body itself – a single piece of stainless steel. To access the movement, one must remove the crystal from the front and disassemble the watch like a 19th-century pocket watch, just in reverse.

Why Seiko designed it this way

A watch case traditionally has three openings through which water can penetrate: the crystal, the crown, and the case back. The back is the biggest weak point because its seal runs along the entire circumference and must be replaced during every service.

In the 1960s, Seiko solved this problem radically for several series: they simply omitted the back. The case is manufactured from a single piece, the movement is inserted from the front, and the crystal acts as the seal. This eliminates one of the three weak points entirely.

The price for this was increased effort in the workshop. The crystal must be removed during every service, requiring special tools, and the hands and dial area are exposed during every intervention. This is precisely why many of these watches today have scratches on the dial – any sloppy service leaves its mark.

This is not the case with this example. The dial is clean, and the watch has been professionally serviced.

The additional note "PUSH SET LEVER, PULL STEM" is intended for the watchmaker: the setting lever must be pressed before the winding stem can be pulled. A workshop instruction, stamped into steel – a detail from a time when it was assumed that a watch would be maintained for decades.

Consistently, Seiko did not stamp "WATER RESIST" on this case, but rather "WATERPROOF". The construction was capable of it.

The Lord Matic in the Seiko hierarchy

The Lord Matic (LM) series appeared in 1968 and occupied the upscale mid-range at Seiko: above the Seiko 5, below the King Seiko and Grand Seiko. It was produced in the Suwa factory – the same facility that developed Grand Seiko in parallel, while Daini was responsible for King Seiko. This internal competition between Suwa and Daini was the driving force that brought Japanese watchmaking of the 1960s and 1970s to a world-class level.

Technically, the Lord Matic benefited directly from this. The caliber 5606 belongs to the 56 movement family – the same architecture upon which the King Seiko caliber 5626 and Grand Seiko caliber 5646 are built. The Lord Matic ran at a lower frequency and had simpler fine regulation than its more expensive siblings, but the basic construction is the same. This explains why the 5606 series is still considered exceptionally robust today.

Dating to October 1969, this watch comes from the first full production year of the series – from the phase in which Seiko still equipped the line with elaborate case constructions like this one. Later 5606s consistently received conventional screw-down or snap-on backs.

The caliber 5606A

• Automatic with manual winding – unlike older Seiko automatic movements, the 5606 can also be wound by hand
• Hacking seconds when the crown is pulled, allowing for precision time setting
• 23 jewels
• Quick-set for day and date
• Bilingual day wheel, Japanese and English

The bilingual version follows the Japanese calendar convention: Sunday is displayed in red, Saturday in blue – corresponding to the markings in the Japanese calendar. A detail not found on European watches that reveals the watch's origin at a glance.

Dial and case

The dial is in a light silver tone with a fine radial sunburst finish that shifts across the surface in changing light. The hour markers are applied, faceted batons with polished flanks, accompanied by slender polished hands and a fine central seconds hand.

The dial is signed with SEIKO, the LM logo, as well as LORD MATIC 23 JEWELS and the Suwa factory mark. The calendar window at three o'clock is framed with an applied border and shows the day and date side by side.

The case follows the design language that Taro Tanaka formulated at Seiko as the "Grammar of Design": flat polished sections, sharply contrasted against brushed surfaces, angular lugs with clearly visible facets. The shape is an elongated tonneau, with only 40.3 mm lug-to-lug at a 35.9 mm diameter – an unusually compact design that sits neatly even on slim wrists.

Condition

This watch is in very good condition.

Technically flawless: it was professionally serviced in Japan in the spring/summer of 2026 – completely disassembled, cleaned, oiled, and regulated. The automatic movement, manual winding, hacking seconds, and quick-set for day and date all work perfectly.

The dial is clean and uniform, without spots, discoloration, or scratches. This is remarkable for a monocoque case, because every service is performed via the dial side, and improper interventions there would be immediately visible. The lettering is complete and sharp, the applied indices are firm and free of corrosion, and the calendar frame is intact.

The stainless steel case shows light, age-appropriate signs of wear; the facets on the lugs and the transitions between polished and brushed surfaces are well-preserved. The case back shows fine scratches from use; all stamps are complete and clearly legible. The crystal is clear with isolated, fine signs of wear.

A new black leather strap is attached.

Technical specifications

• Brand / Line: Seiko, Lord Matic (LM)
• Reference: 5606-7000
• Serial number: 900469
• Production date: October 1969
• Movement: Seiko caliber 5606A, automatic with manual winding, 23 jewels, hacking seconds
• Manufacturer: Suwa Seikosha, Japan
• Functions: Hours, minutes, central seconds, date and day with quick-set, bilingual day wheel (Japanese/English)
• Case: Stainless steel, single-piece monocoque case (movement accessed from the front through the crystal)
• Diameter (without crown): 35.9 mm
• Height: 9.6 mm
• Lug-to-lug: 40.3 mm
• Lug width: 19 mm
• Weight (incl. strap): 43 g
• Strap: New black leather strap
• Crystal: Acrylic crystal
• Service: Spring/Summer 2026, Japan – full disassembly, cleaning, oiling, regulation

For whom

For collectors interested in Japanese case constructions. Monocoque cases are limited to a few series and a few years at Seiko; they tell of a time when engineers solved fundamental problems fundamentally, rather than simply improving existing designs.

For those looking for a high-quality automatic movement with manual winding, hacking seconds, and quick-set, without paying the premium for a King Seiko – despite sharing the same movement architecture.

And for slimmer wrists: 40.3 mm lug-to-lug at 9.6 mm height and 43 g are dimensions that hardly any watch achieves today.

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 vintage watch, water resistance cannot be guaranteed. To protect the movement, the watch should not come into contact with water or moisture.