Go to the Extras menu of the DVD for secrets that relate to the game.
Completion bonus
Successfully complete the game to unlock the parody mode. Parody mode replaces the original text with joke dialogue. Note: This is only available in the Japanese version.
Easier game
It is much easier if you have a Wavemaster in your party, whether it is Elk, Wiseman, or someone else; and also have a heavy blade person. This helps very much. Also keep your other members leveled up with you because you have to use them at times.