Successfully complete the game to unlock the EX mode option. This option allows you to play the game again with the money available at the end of your last game, and unlocks new items.

Repeatedly fail a mission to unlock the G-Squad mode option, which allows the game to be played under an easier difficulty setting.

Have at least two Medixir items, the Leviathan 3, and Vulcan 3 barrels. Use L so you can sway from left to right, keeping the monster in your screen. Take the Boss' HP all the way down until he has only a little remaining. Use the Leviathan 3 to do this, then use the Vulcan 3 for the finishing touch. You will probably have to use at least one Medixir before this point. Make sure you do not use the other. Wait until you die to use it. Do not use any Neo-Psionics to fight him only use Cure 2 and 3 on yourself.