Overall it appears to be a Peugot. I'd rather not submit an expanded over-view. Bocama lugs were used on Fench Bikes. VX rear changers were used on 1980 -1984 bikes of many origins of manufacture, in a priced bike from $300 to $450 at the time,Japnese bikes I own have VX so did bikes from all over the world to some degree,the deraileur could have been changed, I doubt it,you don't think so. The serial # 's not Japan,niether is the over-all "feel" I get from the imfo.It's a mixed bag but it's most likely an early '80s bike. Perhaps with more imfo. and more in-put from other members,you'll gain more insight. 25.4 seat tubes were used on a vast majority of bikes,you may want to ascertain which and when Peugot started using 25.4,older ones were thinner. Just to get it more exact.