Persona 3 FES boss help

I started a game on hard mode, and I'm fighting the boss on the 14th floor of the Thebel block. My characters are level 6 and I have Asparas, Orpheus, Ara Mitama and Angel as my Persona. I can't seem to even get a good strategy going here. Are my levels too low? Once he casts Mazio, everyone is pretty much dead in 2 turns. Leveling up takes too long at the beginning of the game as I'm only getting between 2-8 experience points per fight.

I was hoping to win this fight on 5-7(the day that I'm on) as that's the deadline to get the first document for Elizabeth's request.

EDIT: Whew! I just did it. That was, as the difficulty setting says, HARD! It was a combination of luck and strategy. His first Mazio attack missed two of my characters, which allow me to set, and keep up Cadenza to increase my evasion rate, and also use Ara Mitama to increase defense while Junpei and Yukari pummeled on him with magic attacks, and I could occasionally throw in a Mazio Gem for 50+ damage to bring in the kill.