Black Heart was released in May 1991.
'Black Heart' is not only the title of this game, but also boses' names in Razing's Famous shooter "Battle Garega" and "Armed Police Batrider.". Many staff from UPL joined Raizing later and apparently, they like this name.
Gamest (Japanese game magazine) April 2011, a gamer called 'KDK-takeyuki' recorded a high score of 3,713,700 points on this game.
See goodies section.