Unlock ALL Characters:
At the 'Title' screen press L1, R2, L2, R1, Right, Left, L3, R3.

Full Health:
During gameplay pause the game and press Up, Down, Right, Left, Square(3).

Unlock ALL Items:
At the 'Item' selection screen hold L1 + R1 and press Up, Square(2), Left, Square(2), Down, Square(2), Right, Square(2).

Unlock ALL Mission Layouts:
At the 'Mission' selection screen press R3, L3, R2, L2, R1, L1.

Unlock ALL Story Mode Missions:
At the 'Mission' selection screen press L1, R1, L2, R2, Right, Square, L3, R3.

Unlock ALL Multi-Player Levels:
At the 'Versus' or 'Co-Op' level selection screen press L1, R1, L2, R2, Right, Square, L3, R3.

Unlock Bonus Rikimaru Stage:
At the 'Title' screen press L1, Up, R1, Down, L2, Right, R2, Left or alternatively complete the game with ALL 3 characters.

Unlock Demo Mission:
At the 'Title' screen press Up, Down, Right, Left, X(3).

Increase Items:
At the 'Item' selection screen hold L2 + R2 and press Square(3), Up, Left, Down, Right.

Increase Score:
During gameplay pause the game and hold L1 + R1 and press Right(2), Left(2) on controller two to add 100 points to your score.

Infinite Item Capacity:
At the 'Item' selection screen hold L1 + L2 + R1 + R2 and press Square(3), Up, Left, Down, Right, Square, Up, Right, Down, Left (you will still only be able to carry six different items but you will have an unlimited supply of each of them).

Toggle Special Abilities:
During gameplay pause the game and hold L1 + L2 and press Up(2), Down(2). Then release L1 + L2 and press Square(2), R1, R2.

Display Score and Time:
During gameplay pause the game and press Right(2), Left(2) on controller two.

If you crouch in the hot water springs at the Bamboo Forest when you are low in health your health level will rise.

This doctor-assassin is unlocked as a playable character when you have completed the game once with Rikimaru and once with Ayame.