He's weak against Chrono, actually.
This is a turn-based game where you fight with cards, and so you bring a "deck" with you in combat. You have different kind of cards, ones that are weapons for attack, food ones for healing, and armor ones for defending enemy attacks and such. Run out of cards to use, and you waste a turn "shuffling the deck".
[My teammates attack]
Mizuti:
Chronos Burst IV, Fire Burst IV, Light Flare III, Aqua Burst IV, Dark Flare III.
(450 total damage. Meh-worthy.)
Gibari:
Wave Paddle, Ice Paddle, Dark Paddle, Stun Paddle, Light Paddle
(Played cards right, 64% atk bonus. 800 total damage, sweet.)
"Lady Death":
Knuckle Fist, Claw Fist, Fire Claw, Wolf Claw, {Special Attack} Vanish Grenade
(520 Attack, decent.)
[Enemy's Turn]
Kalas: (Attacking "Lady Death")
Slash [Block], Slash [Block], Slash [Block], Slash [Block], Slash [Block], Slash, {Special Attack} Binding Wind
(290 total damage. I can take a few of those hits.)
"Lady Death" is paralyzed.
Kalas: (Attacks "Lady Death".)
Slash, Slash, Slash, Slash, Slash, Slash, {Special Attack} Dark Blade
(596 total damage. Ouch....)
Kalas heals 596 HPs.
[My turn] (Repeat my first turn, except with fewer attacks since I'm running out of cards)
*20 minutes later....*
"Lady Death"--Almost Dead
Mizuti--Almost Dead
Gibari--Half way dead with nothing but defense cards, so he can't attack.
Kalas--Almost dead as well.
[My Turn]
Mizuti:
(Unable to attack since it has only healing items)
"Lady Death":
Knuckle Fist, Ice Claws, Power Gloves, Power Gloves
(Out of cards)
(392 Damage, bleh.)
Gibari:
(Unable to attack, has all defensive items.)
[Enemy Turn]
Kalas: *Almost Dead* (Attacks Mizuti)
Slash [Block], Slash [Block], Slash, Slash, Slash, Slash, {Special Attack} Binding Winds
(380 total damage)
Mizuti is paralyzed.
Kalas: (Attacks Mizuti)
Slash, Slash, Slash, Slash, Slash, Slash, {Special Attack} Dark Blade
(596 Damage)
Kalas heals 596 HP.
[My Turn]
"Lady Death":
"Shuffling the deck".
Mizuti: Stunned
Gibari:
(All defensive Items still, no attack ones in sight.)
[Enemy's Turn]
Kalas: (Attacks Mizuti)
Slash, Slash, Slash, Slash, Slash, Slash, {Special Attack} Dark Blade
(596 dmg)
Kalas heals 596 HPs.
Mizuti dies.
[My turn]
"Lady Death":
*Uses Sacred Wine and Apple on Mizuti to revive it*
(650 HPs recovered)
Gibari:
(All defensive items)
Mizuti:
Light Flare III, Dark Flare III, Fire Burst III, Chronos Blow III, Fire Burst IV
(420 total damage. Meh)
[Enemy turn]
Long story short, Kalas kills Mizuti again, healing another 596 HPs.