You have google for that kind of questions
You can interrupt her by making series of small attacks to increase the flashing bar at left side of the screen, then hit with an ability to knocks her off her feet for a bit, that interrupts most big attacks from taking place, and you can use just guards to make first hit from any melee attack to deal 0 damage, just guards also cost 1 AP instead of 2 AP to use.
Raise your AGI to max asap from your stats, then the skill that makes the flashing bar on left side of the screen to rise faster, you can essentially keep blocking her melee attacks until your SP is full to annihilate the living fuck out of her with one super attack of your own once your STR and DEF are capped at max on 1st and 2nd rounds.
Also, stock up AP to max before you end the round, you have one hell of an advantage on next round start with maxed out AP.
You can also stop her cast attacks with your cast cancelling skill, that works the same way as the other skills, small basic attacks first to raise the flashing bar, then use the skill to counter her casting.