Sword Cheat:
Goto the "Main Menu" and enter the following:
Left Right(x2) Up X(x2) Square

Level Select:
Load a game and press L2(x2), R2(x2) when the message "Checking Memory Card" appears. Then, a level selection screen will appear when the game begins.

Invincibility and Items:
Pause the game and press L2, R2, L2(3), R2(3), Circle, Triangle, Square, Circle, Triangle, Square. If you entered the code correctly, you will hear a chime and the ninja will turn into a skeleton. Then, you will be invincible with infinite items and lives. Repeat the code to turn back into the ninja while keeping the extra items