This tool is often used for resigning saves. If a save file is tied to a different Profile ID, the game won't load it. Tools like BSD can patch the save with your specific Profile ID, essentially "repacking" the identity of the file.
Look for a "100% Completion" or "Max Stats" save. shinobido way of the ninja save data repack
While the Shinobido community generally supports save repacking as a form of "time-skipping," you must be careful. This tool is often used for resigning saves
Are you looking to repack this save specifically for use on or for the PCSX2 emulator ? Shinobido Imashime Save Game Files for PlayStation 2 shinobido way of the ninja save data repack