Enter the password screen from the main menu and input the following.
Password - Effect
JESSICA PARKER - Allows you to purchase black belt
VICTORIA PARR - Allows you to purchase M16 badge
SARYL HIRSCH - Allows you to purchase the sunglasses
RENATO CELANI - Allows you to purchase the fugu
6943059 - Allows you To purchase disk 6 after completing game
9603717 - Gallery is added to secret mode
6894098 - Outfit change is added to secret mode
9785711 - Allows you to select level HARD
5204025 - Get 10000 spy points
4298359 - Everthing at shop is at half price!