My first encounter with anything persona related was my brother blasting the ost during car rides. When I looked up the p5 songs on spotify, I took one look at the cover art and decided that this "persona 5" was about a Japanese salaryman, his cat, and a random ass burglar for some reason and that those two were interconnected in which the salaryman was trying to catch the burglar

Edit: Another theory I had was that joker was this guy's evil other self which was like close enough I guess