Classic & Vintage - Unknown 80's Japanese Road Bike i.d. Help Please

Long time, my friends..... Hope everyone is well. Can the Japanese experts help me with an i.d.?
Stumbled across this at a GS this weekend and the parents didn't know much about its history as the hipster youngsters had flat-blacked it to be "stealthy" before leaving for college...:(
Of course they left this behind when their friends told them they "had" to have track bikes for getting around college, and being cool...

I sensed upon lifting that it is at least along the lines of Tange Champion #1/2 or maybe Infinity so I grabbed it.
The sad thing is that I seem to recall having a very similar bike in my collection some years ago; Nondescript rear drops w/ micro adjusters, simple but elegant lugs, unusual cable guides on the BB shell, Signature series cranks, unusual Araya Red Label 27 X 1" rather than 1 1/4, a mix of 600 and LePree, etc...
Serial is stamped straight across the BB and reads "MA XX856" Wondering about Nishiki but am unsure.

Appears that it had decals only as I don't see any sign of rivets ever holding a head badge on the head tube.

The reason that I'm interested in this bike is because I'd like to try out Grant Peterson's sizing theory about using larger frames with a shorter TT, so this is a perfect candidate for me.

Thanks for your thoughts folks...

Lugs look awfully plain for Champion 1 to me. I would expect to see a fair amount of chrome as well for Champion 1. Looks like someone to a grinder to that rear drop out.

Kind of has a Fuji look to it to me.

Not sure, weight-wise the bike is comparable to or lighter than my Serotta, Miyata and Paramount's.....and they are all 56/57cm so it's got to be some sort of good CrMo.. Parts are certainly only low/mid-range, but this happened to many good framesets in the 80's. And who knows how much of this is retrofitted....

I can't count the number of sweet Champion/Infinity/Prestige Univega's and Nishiki's that I've had or seen that had plain lugs and little to no chrome...
I'm hoping that someone will recognize the serial format before I proceed...
I am seeing what appears to be chrome on the stays and fork but there's no way I'm going to start stripping until I know what this thing is. Been there, done that and don't want to go back....

Sorry for the poor dropout image... No grinder, just a bad angle shot on my part....

Good call on the Fuji, I never thought of that over Nishiki. I can't recall if Fuji's switched over to head tube decals or if they kept the Mt Fuji head tube badge into the mid-late 80's... There are no signs of any holes ever existing on the head tube.

Darn Hipsters, blacking out a perfectly good bike..... The kid who did it did quite a good job of laying it on thick and smooth. It doesn't want to come off :^(

I went throught the same kind of inquiry about four years ago when I bought an all-105 bike from 1986, based on the Shimano date codes; it had been branded "Hunter" and was a good-looking 62 cm bike in my size coming in at about 23.5 pounds. Best theory was that it was a Kawamura frame, imported, built up and decaled by a stateside firm. The best answer I got is that it was a UJB .... Universal Japanese Bike. Whatever it is, I like it.