Put the CD into your computer and look in the root directory. There you will find several BMP files for your viewing pleasure.
Play as Uon
Accumulate over six hours of game play. Alternatively, successfully complete story mode with all ten characters.
Play as Kiss
Accumulate over twelve hours of game play. Alternatively, unlock Uon then successfully complete arcade mode with all characters.
Play as Burn
Unlock Uon and Kiss. Then, successfully complete story and arcade mode with all characters including Uon and Kiss.