Mitsubishi and Faber-Castell had some crossover events in the 1990s, and my guess is these M5-530 pencils emerged during this era.
Specifically, there was an Uni-ball collaboration with Faber-Castell that yielded a black MP styled after the ubiquitous Uni-ball pens of the time.
And then both Mitsubishi and Faber-Castell released their own versions of the M5-530 double-knock seen here (though Mitsubishi did it better with 4 color offerings; I think Faber-Castell only offered black).
It’s always nice to identify a new model number, but this period in Mitsubishi/Uni’s history is extremely weird, as very few pencils were released under the Mitsubishi brand after the mid-1980s (everything began to carry a sub-label of either Uni, BOXY, or Exceed).
These open source double-knocks appear to have bucked that trend, though it’s always possible this was a 1980s collaboration that preceded the Uni/FC collabs of the 1990s.