All Weapons:
Hold L1 + R1 and press X, Triangle, Square, Triangle, Square, Circle at the item selection screen. Then, release L1 and press L1 again.

Level Select:
Get to the mission select screen and hold R2. Then press Left, Left, Down, Down, Square, Square, Triangle, Square. You will now be able to select your levels.

Increase Item Inventory:
At the item selection screen hold L2 and press Left, Left, Down, Down, Square, Square, Triangle, X.

Full Health:
Pause the game play and press Left, Left, Down, Down, Square, Square, Triangle, Square.

99 Items:
On the item menu, hold L1 and then press Left, Left, Down, Down, Square, Square, Triangle, Square.

Ayame's Butt Showing Armour:
At the item select screen press Left, Left, Down, Down, Square, Square, Triangle, Circle. You must have the Ninja Armour first for this to work.

Unlock all secret ninja tools:
Hold R1, Left, Left, Down, Down, Square, Square, Triangle, Square.

Unlock secret ninja tools:
When select weapons comes up hold R1 and press Square, Square, Triangle, Triangle, Right, Right, Up, Left.

Japanese Voice Over:
Do the following on the stage select screen. Hold L1, Left, Left, Down, Down, Square, Square, Triangle, Circle.

Enable Enemy Layout Selection:
On the stage select screen, hold R1, and press Left, Left, Square, Square, Triangle, X.

Debug Mode:
During a game, press the pause button. Then hold L1 and R2 together and press Up, Triangle, Down, X, Left, Square, Right, Circle. Now release L1 and R2 and press L1, R1, L2, R2. Wait a moment and then press Start followed by L2 and R2. You can now access the menu at any time by pressing L1 and R2. The menu allows secret weapons, enemy layouts, summoning as well as other effects.

Increase Items:
At your item select screen hold down R1 and Square, then press Right, Down, Left, Up and all your items should increase by one.