Lol, I totally forgot about Torikabuto. I think I thought he was like a mosca or something, since he was so gigantic and we never saw his face or something. Clearly, I fail.

OR MAYBE - the entire series is one giant practical joke set up by Primo and added onto by the various bosses that followed. And the next arc will be set a few years into the future and be about Tsuna starting his own practical joke plans for the 20th boss. At this point I'm willing to suspect anything is possible.