"Batman" is initially implied to be a shapeshifting ninja in the original version of the game. After Musashi defeats the ninja in his first form (which resembles Spider-Man), he will transform into Batman and continue the fight.
As SEGA did not have the rights from DC Comics to use Batman's likeness, they were forced to edit his portrayal. In all later versions of the game, "Batman" appears as a demon-like creature who bears little resemblance to the superhero (though it does strongly resemble Devilman, a Japanese manga character). However, the frames of animation and bat sprites remained nearly unchanged.