This would have made the movie really cool, oh well.
Johnny should have become friends with Daniel after KK1 and gone with him and Mayagi to Japan and gotten really badly beaten up (hospital) by Chozen with Daniel's final fight against Chozen being partly to avenge his friend.
Johnny was the least evil of the villains and redeemable and if not that his story should have continued in some other way, maybe a spinoff, but with him as a good guy, maybe trying to make amends for the jerk he was before learning humility and also maybe a slightly traumatized person who was strangled nearly to death before being rescued by Mayagi.