The Legend Of Dark Witch Play as Princess Riva
Successfully complete the game with Zizou to unlock Princess Riva.
Fill bonus gauge
Defeat Klinsy the librarian, and obtain the Dia Missile spell. Use the spell in an area of any level without any enemies in range. When used while the crosshairs are not visible, your bonus gauge will fill a small amount. Repeat the process until the gauge is filled, allowing you to get any desired upgrade.