Since the programmers didn't intend anyone to play as Kotaro, Jubei the Pimp, or Shin-Onimusha through the entire game, you'll sometimes get stuck and won't be able to progress. With activator codes (button press codes) applied to each character modifier, you'll be able to change back to the character that is normally played if you ever get stuck. (Sometimes the game will just plain lock up, so be careful where you use different characters, and who you save with!)

To get these codes to work properly, simply choose a character you wish to become, enter a door, and hold the correct button combination while the next section of the level loads. For example... Let's say you want to start the game as Oyu (the Hooker version); simply press and hold RIGHT (on the D-PAD) and R1 while the intro movie is playing. When your character appears on screen, it will no longer be Jubei... If you want to change Hooker Oyu into Kotaro, enter any door and hold UP (on the D-PAD) and R1 until the next screen is loaded.