The 1970s Seiko 6139 automatic chronograph had well over a dozen variants, and one of its most unusual was the black PVD variant - like this matte black PVD 1972 Seiko 6139-8010 here, sold only in Japan.  Seiko placed their movements into multiple highly unique cases, leading to a plethora of out of the ordinary shapes and sizes, and this PVD 6139 here is a fantastic example of this.

The 6139 - a historical movement in its own right - was one of the first automatic chronograph movements created, and counts itself within the ranks of Zenith/Movado’s El Primero movement.  Back in the 1970’s, Heuer and the El Primero had taken a foothold of the entire sports watch industry by racing to become the first to produce an automatic chronograph. 
 
It has been widely debated who really won between the two, but in the background of this skirmish, Seiko quietly created their own, beating the Swiss at their own game – the Ref. 6139.

During 1969, Seiko put the final touches on its 6139 - although the company officially began selling these in May 1969, the 6139 had already begun appearing in automatic chronographs as early as January of the same year.
 
Seiko published the first advertisement for their new automatic 6139 chronograph in February 1969, easily beating the Swiss.  But the Japanese company wasn't satisified with this - it was concentrating that year on the release of the world's first quartz watch, the Astron, which would completely disrupt the watch world as it was known at the time, again much to the chagrin of the Swiss watch industry.  We have 6139 dials dating back to October 1968, indicating Seiko beat all other rivals to produce the world's first automatic chronograph.  Period. 
 
The 6139 was the first chronograph to have a vertical clutch, a feature considered by many to be one of the hallmarks of a superior automatic chronograph movement.  The 6139 also features an automatic column wheel timing control, vertical coupling mechanism, and is an integrated chronograph – the first in the world – which means the entire 6139 movement was designed and built to be a chronograph, vice being an automatic movement with a mere timing module added (**cough cough** the Calibre 11).

With this movement, Seiko set the standard, which was followed by the Swiss watch industries 20 years later.  The same movement configuration was adopted by Rolex when it made its own in-house movement for the Daytona in 2000, 30 years after Seiko released the caliber 6139 and 6138.

This Japanese Domestic Market (JDM)-only matte black Seiko 6139 comes on its original bracelet, and with nylon strap, springbar tool, and rugged travel case.