To adapt part 4 as an anime, they had to cut out some material for time reasons. That's normal, but it makes the anime miss some great moments, like this:
...or Cheap Trick ordering pizza for Rohan to try and get the delivery guys to see his back:
...or Josuke's excuse to stop Rohan from biting down on the alien dude disguised as dice:
lol just realized all these moments involve Rohan in some way. guess the animators hate him