Seiko

1. The intriguing caseback inscription which translates roughly as: "In honor of meritorious services - President of Japan National Railways" indicating this was a retirement watch for an employee of what is now JR. In addition to watches, I'm also interested in trains so this rail connection stood out to me as very cool! 

2. The case design. While not a GS, it clearly benefited from the Tanaka "Grammar of Design" treatment, and shares a lot of design features with the famous 44GS

3. The movement. The 56xx movement was shared by both King Seiko and Grand Seiko lines, though in the finer guises it was tuned up to 28,800 (from 21,600) and more carefully regulated. The movement does have a weakness, which is a plastic component for the quick-set date. These often break. For this reason, these are available at much more accessible prices than similar watches. However, it should be noted that the mere fact that it has a quick-set day/date is impressive, as Seiko launched this movement in 1968. For context, it wasn't until 1988 that the Rolex Day-Date featured quick-set day/date adjustment. I'm not aware of the service history of this example, but on the wrist it's been keeping good time (roughly -8s/d).

Enjoy the pictures!