What are the differences between the difficulties?
Easy has a 0.7x multiplier for all enemy stats. GRADE has a 0x multiplier. Normal is the default difficulty which determines the other three. Hard has a 2.5x multiplier in enemy HP. Attack stats are multiplied by 1.2; Defense stats are unaffected. GRADE has a 1.5x multiplier. Unknown has a 5x multiplier in enemy HP. Physical attack has a 3.5x multiplier; Magic Attack has a 3x multiplier. Both defense stats have a 2.5x multiplier. GRADE has a 2x multiplier. Different EXP modifiers from the GRADE Shop may be necessary for higher difficulties, but thats up to you.