Ok I am relly liking this. MC knows what he wants to do, has the guts, companion and means to see it through.
Also, if you played Persona 5, then you should know about Arsene, and you should know about Lupin and "white glove thieves" and other rougues in general.
I can see the author being inspired by P5 to START writing about an Phantom Thieves Isekai, but the concept of Phantom Thieves existed way before Persona 5 guys.
Hell, ISHIKAWA GOEMON was precisely this, and even ended up as a Persona in P5.