Screenshots from the PC Engine version of the game.
(1)-The first thing that makes us think that it is an unfinished version of the game (and that's amazing) is that the platforms locations does not match any of the first seven levels of the PC Engine version, neither the background. We can see in the lower right part of the screen, two completely black mountains overlapped. There are another strange elements like the numbers 14 or 15 and musical notes in the middle-top part of the screen.
(2)-In the Pc Engine version, in top of the player 1's score, the name of the main character (Bubby) appears at the right side of the lifes counter. In this photograph, we can read (using a bit of imagination) that "BUBBY" does not appear, but "1P". This term was used by Taito in almost all their arcade games in 1990 (for example, Growl, Ninja Kids, Liquid Kids, etc..). However, during the 80s, "player 1" was almost always indicated as 1UP (for example, Arkanoid, Bubble Bobble, Rainbow Islands, Rastan, etc...).
(3) The character set in PC Engine Parasol Stars is from 1991. It is curious to see that it uses a font that is almost identical to those used by Taito in the majority of their arcade games from mid 80s until 1990. 'Growl' (1990 arcade version) uses a very similar font to that of the PC Engine Parasol Stars, and here we are: there is no Taito's arcade game, 1991 copyrighted, using this font. This does not prove anything but it's strange.
Where does this ghost photo come from?. This photo could be the only proof that an arcade prototype of Parasol Stars existed.