SUPER WEIRD FIGURE! Too early to be a modern Gashapon candy toy, this is a vintage 1983 Bandai mini figure (4") of Mefilas Seijin (aka Alien Mefilas or Mephilas) from the Tsuburaya Ultraman TV franchise.
This figure is noteworthy because it does not appear to be made out of soft vinyl like practically every other Bandai figure in history. It has a feeling like blow mold acetate or polyethylene - more like a celluloid carnival doll than a sofubi. It's a mystery, I tell ya.