That Ex guy, I'm guessing, is constantly implementing the "intent" of chasing on to the gang.
For example, in the hospital, he told the gang the old man's location, then they chase him and got in danger. The same pattern is happening with Yatsuho.
If you think the main villain is joubin then your a small brain I've seen a lot of comments saying he's the main villain no comments on this chapter tho and here's why I don't think he's the main villain because his stand is weak as fuck his ability is to make heat not move in your body of whatever if he's near just punch the shit out of him his ability should stop and if he's not near hell put the heat on an object I'm pretty sure that's what happend to snake dude and jouske would be smart enough to think hey this shouldn't be hot maybe it's a stand I don't think I should touch it there is my explanation because he's weak as fuck if he wasn't that weak then ya maybe but I think he's a secondary villain
I'm sure that Tooru is the main villain. Why doesn't Yasuho got affected by the rain? Why is he there everytime the head doctor arrives?
He must be the main villain.