Below are the codes for unlocking new music tracks.
Army Corps of Hell: codes (music tracks) [Vita] Free Download
More precisely, special robes, wearing which, you will hear the specified song.
G75i8K8a – Gouls Attack!
GUK218Jh – GxSxD
KB2p3tAs – KING’S-EVIL
K77w3P5a – KNIGHTS OF ROUND
RJ53z42i – Rachel Mother Goose
S4R29dlu – Rebel-Survive
U541337k – United