Considering we have no idea who this guy is is it possible he is in P5?
We know a bit about him. We know:
- His name's "Sho Minazuki."
- That he has a Yasogami outfit around his waist for some reason.
- That he wants to "slit everyone's throats."
- That he's probably not allied with Shadows either since one of his intro has him slice one in half.
- That he can fight without a Persona and his title is "The Lawbreaking Pun Machine."
- That he gains or uses a Persona at some point and his portrait looks more malicious when he does and his title becomes "The Defaced Dark Messiah."
- Is presumably behind the events of P4A and P4A2.
All that said, I don't think there's anything linking him to P5 aside from the color red while there's plenty just linking him to the P4A saga, so it's too soon to come with a conclusion either way, but the safest bet currently would be that he's just a P4A character.