Batman - Return of the Joker [Model DMG-B5A]

Secret bonus:
At the title screen, press Left + B + Select. The game will immediately start with a different starting sound, rather than a regular bat wings sound. Now on every boss stage, when the player's health drops below the 3 points, but the boss still has more than 16 health points, the friendly support character will fly over the screen dropping up to 4 heart bonuses. However, this bonus may be triggered only once for each boss.