Wow, some pure evil students in this class, par the course for edgy dumpster fires.
I was afraid that Yui would turn into a monster from Saeko's unhinged parenting, but she remains to be one of the very few kind people in this manga. If the entire class is not shit, I want to at least hope she becomes friends with Kyouko, who she sided with.
So I was right. Iwakura is a customer, but his payment isn't money, it's doing the dirty work for Saeko. And now the useless teacher is probably going to see himself ensnared in a badger game or something similar depending on whether Saeko seduces him or destroys him. The best he can hope for is survival and a renewed focus on disciplining his class. Worst is death and replacement by a new teacher who will actually enforce their authority on the bullies.