Completion bonuses:
Beat the game to unlock the “Extra Contents” option, “Hyper Speed” option, and Hard difficulty. To change the speed, turn on the “Hyper Speed” option, then press R for high battle speed. Press R again for hyper battle speed.

Unlockable characters:
Unlock the following characters by performing the corresponding tasks:

Cruz – Go to the small area near the BF 23 exit. Another exit will appear. Go there, and enter BF 23.5 to find Cruz.
Mistel – Search both villages in BF 13 to go to BF 14 I/II and find Mistel.
Pamela – On the Hard difficulty, go to BF 23 or BF 24, and put Nietzsche next to her.
Russell – Go to BF 20, move left, and save Flone from Aegina. Then, place anyone next to Russell in BF 21.