Saw this for sale locally. It reminds me a little bit of a constellation I used to own.

 

SM120m from the 1990s. 36mm case very like that used on the mid size SMP. A big seller in Japan.

 

Started life in 1993

And became and anniversary piece in 95 — with the wave dial

 

Casebackshould be anniversary stamped

 

It's a 2501.31 or close relative I believe.