The Black Heart MK-II, also know as Black Heart, is a combat ship that serves as a boss from Battle Garegga. Much like every single enemy in the game, it was created by the Wayne brothers at the request of The Federation, and used by the organization for their evil purposes.
It is fought twice in the game, in the 4th stage (Clouds) and in the final stage (Airport) just before the final boss. Not only it is very fast, it's wings are invulnerable, meaning only it's tiny body is vulnerable. The wings conceal most of it's weaponry, though it can also attack with it's fire engines.
The Black Heart makes a cameo appearance in Armed Police Batrider as a hidden boss, which is fought randomly on the Zenovia Sewage System stage if you're playing with any of the Wayne brothers.