CPK

CPK is an archive format used in  all Bayonetta Games. It was developed by CRI Middleware. Usually, most game data except for executables is stored in compressed CPK archives.

CriPakGUI
CriPakGUI can open and extract most CPK files easily with its very user friendly interface. You can download it from here.

QuickBMS
aluigi's file extractor | QuickBMS has scripts in .bms format for CPK archives. Run quickbms.exe, select cpk.bms, and then select your CPK file. It will automatically extract the contents to the directory of your choosing.