PS4 - PS Vita Cross-Saves

What are cross-saves?

Cross-saves refer to saves that are compatible on 2 or more systems that can be used interchangeably.
This guide will cover PS4 to PS Vita saves and vice versa.

Both PS4 & PS Vita need to be hacked/jailbroken. Firmware doesn’t matter, game versions don’t matter either.
For PS4: Apollo Save Tool
For PS Vita: VitaShell
Games need to follow the same or similar structure on both platforms (PS4 / Vita).

Open Apollo Save Tool > HDD Saves > Your game.
Export Decrypted Save Files and select your USB drive.
Apollo will create a folder on the USB drive (PS4 > APOLLO). The save file should be called SYSTEM.DAT.
Simply rename SYSTEM.DAT to system.bin (make sure you do rename the extension dat to bin and not system.bin.dat).
Some games might have different naming schemes for the files but as long as both the Vita and PS4 have similar naming schemes then the games will most likely work.
Copy the save to your Vita (any folder).
On PS Vita make sure you open the game and wait until it makes a save. You need a save to be created so it can be replaced.
Open VitaShell and navigate to ux0 > user > 00 > savedata.
Once you see your game ID, press Triangle button > Open decrypted.
Copy and replace system.bin.
Done.

Note that “Checking DLC content” will show again on your Vita. A bit annoying if you have all of them, you will have to spam X. This is only a first time issue tho.
Tested and confirmed working on Persona Dancing series (3, 4 & 5) & Gundam Breaker 3 Break Edition,
To do the same but from Vita to PS4, just follow the tutorial but backwards.