Well it looks like I've unlocked everyone I could (only 2 blank spaces left in the character selection screen). After playing as Eroyama (the guy with the red necktie tied around his head; also he's one of the last unlockable characters to be unlocked) I found a few interesting things about him:
1. If there's a girl nearby (friend or foe), Eroyama can recharge his health by groping the girl - press punch or kick (yes even your Auto 2p partner - which made for a hilarious game and thus lots of this happened [Minmin was my Auto 2P partner]:
).
2. His "special" attack is a Molotov Cocktail. It's tricky to use (because it's slow to execute, which can make him vulnerable), but when in very close quarters, the impact of swinging the cocktail actually inflicts heavy damage to opponents (even more than the blast and flame from a thrown cocktail). Also, it doesn't drain the "SP" bar so he has unlimited ammo.