Go to the set up menu and change the button configuration so that you will jump with A. Have the game play by itself and the demo will do some unusual things.
Alternate female character
Successfully complete the game to unlock an alternate version of the female character.
Invincibility
Successfully complete the game under the normal or better difficulty setting and obtain a rank of 23/23. Note: Some falls will still be harmful.
Level select
Successfully complete the game to unlock the "S-Continue" option that allows any level to be played again.
Play as Boss
Successfully complete the game with a devil class rank under the very hard difficulty setting. The last Boss will be playable, with unlimited hit points but limited ammunition.
Super jump
Jump on an opponent's head and immediately jump again to jump higher than normal.