Stellaris was the in-house watch brand for Sears, Roebuck, and Company department store for years, incorporating Seiko and Swiss automatic and manual-wind mechanical movements - and this sharp, full-serviced near new-old stock 1960s Stellaris Ref. 6S 5026B mechanical watch here is no different.  
 
Japanese watch company Hamazawa Ltd – founded in 1954 – had an unofficial relationship with Seiko.  In the 1970s, Hamazawa took out several joint patents with Epson (one of the three core companies of Seiko Group in contemporary times) on non-watch related items.  
 
Hamazawa appeared to have sold a lot of movements to various Japanese and foreign watch companies, and in 1983, it merged with two other companies one of which was a major watch case supplier for Seiko-Epson.  Subsequently, in 1986, this company was taken over by Seiko.

That said, we are getting ahead of ourselves – in the 1960’s, Hamazawa released the 5000 family of movements, both automatic and manual wind.  Of note, the self-winding mechanism uses portions of Seiko's Magic Level System. 
 
Back when this watch was made, Hamazawa was most likely somewhat independent; however, the mechanism on the 50xx movements (like the one here) required a license agreement with Seiko who held the patent at that time.  The Hamazawa/Seiko movements were sold widely overseas and may be found in U.S. brands including Sears and Benrus, and the British brand Astral.
 
Although Seiko produced Stellaris for Sears, preceding this, Stellaris was a brand name registered in 1963 by Mondia;  while not a well-known brand, it produced some intriguing watches, such as the Mondia “Big Eye” chronograph and the Top Second.  It also put out a watch model called Stellaris with an unusual fluid case.  
 
And we aren't the only ones that love Stellaris watches - Fratello's Mike Stockton noted about a similar-in-design Stellaris diver that, "It’s a watch with a likable dial, enigmatic branding, 'crippled' hour hand, juicy lume, and a cosmic treatment to the crown grip...this Stellaris is my kind of watch."  
 
But did Mondia and Stellaris evolve to be separate watch brands?  No idea – another mystery lost to the ages, akin to how both brands would become victims of the Seiko-initiated Quartz Crisis.  Fratello speculated, “Mondia was used as support to make Stellaris trustworthy." 
 
"Or, I suppose another possible scenario is that the Mondia Stellaris became so popular that Mondia decided to make it a separate brand featuring its own range of watches.  And there were quite a few of them, mostly later Stellaris electronic models.”  Regardless, the Stellaris font and symbol didn’t change after it was established as a stand-alone brand, the clearest evidence of the relationship between the two.
 
At its 1886 inception, American company Sears - run by Richard W. Sears, a railroad agent - sold watches by mail order catalog - much akin to Amazon at its founding selling books, pocket watches were Sears' first commodity, but it would gradually add substantially to its offerings - just like Amazon.
 
This Stellaris mechanical comes on a premium nylon strap, and with a leather strap, rugged travel case, and springbar tool.