Episode 5.
I shall proceed to give myself a pat on the back for guessing the room switching, Chihiro being a trap, and one of the victims' notebook being "borrowed". But I have to admit I really thought it was Fukawa who killed after finding out Chihiro's a boy, and not that Togami was just making a statement by messing with a dead body. Even if I did manage to pull off a better guess next time, I'll just be accused of playing a game I didn't.
The punishment felt like meh to me, just didn't click at all.