Based on that link, Maestro would be a Matsumoku-made instrument. The visual elements of that bass are ALL Matsumoku. The black tuners on the bass in the first photo are pure Matsumoku and I've had the identical tuners on an Aria from the early 70's.
That factory made Epiphone, Univox, Lyle, Aria and a number of other brands, so they did a lot of name-branding for small lines. Workmanship is good, electronics are average, but a well maintained one is a good player and not that hard to work on if you need to update pickups or electronics.