Alternate costume colors:
Press the various Punch and Kick buttons while choosing a fighter on the character selection screen.

Fight as Inoz:
Accumulate over two hours of total game play. Then, hold L while choosing Mamazo at the character selection screen.

Fight as Darkness:
Accumulate over five hours of total game play. Darkness will now be selectable at the character selection screen.

Stun rate option:
Accumulate over ten hours of total game play to unlock the "Stun rate" option.

Magic limit option:
Accumulate over fifteen hours of total game play to unlock the "Magic limit" option.

Combo limit option:
Accumulate over twenty hours of total game play to unlock the "Combo limit" option.

Magic free option:
Accumulate over twenty five hours of total game play to unlock the "Magic free" option.

No damage option:
Accumulate over thirty hours of total game play to unlock the "Magic free" option.

Hint: Easy options:
To unlock the additional options easily, simply leave the game on overnight. Then, manually save the game by using the "System data" option.