It's been 85 chapters and we still don't know who the main antagonist is. It's interesting because in all the other parts you already know who the antagonist is even if his, specifically Diavolo's, face hasn't been revealed yet.
@AltAidey I understand what you mean, but what I said is true since some people believe it could be the head doctor or even Tsurugi. Maybe in the next chapters we'll be able to confirm it, but for now I've basically narrowed it down to 3 characters.
Chapter 86 was probably the worst character of part 8 I mean omg a lot of information is just being repeated as if Akira is dragging this final arc on purpose