If you go through MP fast get a Jr Boogie Familiar. They heal a lot of MP frequently.
Spoiler!
"From now on, time and time again, again and again you'll have regrets,
again and again you'll be hurt, again and again you'll cry...
But if for each of these, you waste your life looking back,
one day, it'll give you a terrible fever... I just want to let things go,
so return as if you never came, and I'll surely be happy..."