The following is a list of passwords that will unlock bonus content (which includes additional missions, characters and tank stickers) in the extras menu in Valkyria Chronicles 2.
This list covers all passwords posted thus far in Sega's official blog.
Blitz Logo Sticker - VWUYNJQ8HGSVXR7J
Edy Nelson Sticker - R5PT1MXEY3BW8VBE
Edy's Squad - CR6BG1A9LYQKB6WJ
SEGA Logo Sticker - 6RK45S59F7U2JLTD
Skies of Arcadia Sticker - WVZLPTYXURS1Q8TV
Unlock After Burner Climax Tank Sticker - C9SAGP8M7PJ84H5S
Unlock Alicia Gunther Sticker - K1C7XKLJMXUHRD8S
Unlock Alternative G Cadets costumes (Cosette, Ali, and Zeri) - NL45TX9F8VRSUKGR
Unlock Character Emelia (Phantasy Star Portable:2), two new missions, and Little Wing Tank Sticker - FSHL2DTP1EVB52AN
Unlock Crazy Taxi sticker - 38WV17PK45TYAF8V
Unlock Dr. Ivo "Eggman" Robotnik Sticker - GVFX8GA73FDWHQUS
Unlock Faldio - GWNU95RSETW1VGNQ
Unlock Gallian Military Sticker - TXU14EUV74PCR3TE
Unlock Isara Gunther and Isara's Dream Sticker - 37LRK5D214VQVFYH
Unlock Nei (Phantasy Star II) Tank Sticker - 9H1FHVBV2YAZE3A1
Unlock Phantasy Star Zero Rappy Sticker - HPF2B7ASMWV5798U
Unlock Prince Maximilian & Imperial Flag Sticker - H73G4L9GLJR1CHJP
Unlock Resonance of Fate Tank Sticker - UJH5YB4Z7E33VCJT
Unlock Rodin Sticker (Hot!) - YLBWA9UFTHQ3ZM1E
Unlock Selvaria - 53K8FKGP1GHQ4SBN
Unlock Sonic the Hedgehog sticker - CUP34ASEZ9WDKBYV
Unlock Super Monkey Ball Sticker - 7JMNHZ83TGH7XFKT
Unlock Yakuza Sticker - QAKVXZTALF4TU7SK
Vanquish Tank Sticker - BUNLT4EXDS74QRCR