There are two forms of encryption used for Disgaea 5 save files.

The first type is a weak and simple series of bitwise operations.

decrypted = (plaintext » 4) | ((0xF - (plaintext & 0xF)) « 4)

The Disgaea 5 PC trial uses this encryption for the entire save file, while the final version uses it only for the first 0x1C0 bytes.

The second type is a simple 64-bit XOR. Simply XOR every 8 bytes with 0xE76FCBE3F6D46A37. The final version of Disgaea 5 PC uses it for every byte after offset 0x1C0 in save files.