By getting 100% completion you will get:

Intro Sequences from the arcade game
Art Gallery Pictures

Hold start when choosing a stage in versus or training mode to play an alternate stage.

At the main menu, hold down L whilst selecting Option.

In TRAINING or VS mode, hold START when you're selecting the stage to get alternate background colors.

Enter the following at the character select screen:

Oboro Bishamon - In all Modes highlight Bishamon, Hold Start and press any P or K
Shadow - In Arcade Mode Highlight "?" and press start 5 Times then press any P or K
Marionette - In Arcade Mode Highlight "?" and press start 7 Times then press any P or K

At the character select,highlight ? and press start(x7)then press P or K.

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At the character select,highlight ? bishamon,hold start and press P or K.=]

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At the character select,highlight ? and press start(x5) then press P or K.=]

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Illustrations - Complete the Tower mode to 100%
'Hunter' Endings + Intro - In Arcade choose 'Hunter' and select 'Hunter' with the characters that have availible endings. Once all are complete the intro w
Jedah 2 and Pyron 2 Ending - In Arcade choose 'Savior' and select 'Savior 2' with either Jedah or Pyron. Try to beat all characters without losing.
'Vampire Savior' Endings + Intro - In Arcade choose 'Savior' and select 'Savior' with the characters that have availible endings. Once all are complete the intro w
'Vampire' Endings + Intro - In Arcade choose 'Vampire' and select 'Vampire' with the characters that have availible endings. Once all are complete the intro