"Special K Persona 4" gives me this on google, Special K is used in many games so perhaps you just didn't find the right now, here you go https://steamcommunity.com/app/1113000/discussions/0/2441461920666858712/ Thank you for the link! I don't know how to actually use it, though, and all ...

You didn't provide a link to SpecialK_P4G, which is unfortunate; I can't seem to find any mention of this set of files anywhere else, either.