Play with all character in story mode to unlco this option.....
To get the extra costumes for any character, beat the game with that character. For instence if you beat the game with Danzaiver you get his extra costume in the vs mode or the 1 player battle mode.
Play as Kakurine to unlock Ihadurca as secert character!!!!!!!!!!
To play as boss and access the hidden stage, beat the game with 3 different characters in story mode.
To be able to play as Ihadurca, beat story mode with Setsuna.
Each time you play a character in story mode you will unlcock there biography...
Set the difficulty to Hard and then beat 1P Battle Mode with any character. Then,after doi'n that,go to options click at Extra and finally at Voice Collection
Each character you beat in story mode will earn you 7 new postures.