All characters:
     At  the  title  screen, press Square, R1, Square, R2, Square, R2,
Square, R1.

All Shu generals:
     At  the  title  screen,  press  Square,  Square,  R1, R1, Square,
Square, R2, R2.

All Wei generals:
     At  the  title  screen, press Square, Square, Square, Square, R2,
R2, R1, R1.

All Wu generals:
     At  the  title  screen,  press  Square,  Square,  R2, R2, R1, R1,
Square, Square.

BGM Test option:
     At the title screen, press L1, L1, L1, R1, R1, R1, L2, R2.

Opening Edit option:
     At the title screen, press R2, R2, R2, L2, L2, L2, R1, L1.

Free mode side selection:
     At  the title screen, hold Triangle and press R1, L1, L2, R2, R1,
L1, L2, R2

Unlock bonus characters:
     Beat  Musou mode with the following character to unlock the bonus
characters:

A member of the Shu Kingdom - Unlock Huang Zhong, Ma Chao, and Jiang Wei. 
A member of the Wei Kingdom - Unlock Xiahou Yuan and Zhang Liao. 
A member of the Wu Kingdom  - Unlock Taishi Ci, Lu Meng, and Gan Ning.
One member of each kingdom  - Unlock Diao Chan, Dong Zhuo, Yuan Chao, and 
                              Zhang Jiao in free mode.
One member of each kingdom  - Unlock Side Selection in free mode. 

Alternate introduction sequence:
     Finish Musou Mode with any character.

Free Health:
     Locate a save point in the game (this will also work if you don't
have a memory card). When the playstation asks you if you want to save
you can either save or decline to save. You can now return to the game
and you'll have all your health restored.

How to get Lu Bu:
     You must defeat 1000 enemies on the second stage.

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All characters (Japanese version):
     At  the  title  screen,  press  Square,  Square,  L1, L2, R1, R2,
Square, Square.

All Shu generals (Japanese version):
     At the title screen, press Square, R1, R1, R1, R1, R1, R2, R2.

All Wei generals (Japanese version):
     At the title screen, press Square, Square, Square, L1, L1, L2, L2.

All Wu generals (Japanese version):
     At the title screen, press Square, Square, L2, L2, L2, L2, L1, L1.

BGM Test option (Japanese version):
     At the title screen, press R1, R1, R2, R2, L1, L1, L2, L2.

Opening Edit option (Japanese version):
     At the title screen, press L1, L2, R2, R1, L1, L2, R2, R1.