I don't think there is any anime character I genuinely hate, but if there is one, it's probably that whiny four-eyes neighbor boy from Minami-ke Okawari. What was even the point of the character? Besides being an annoying wimp in, like, every situation, he didn't really add anything to the series yet somehow got loads of sceen time. Even worse that he was apparently an anime-original character who some people must have thought was a good idea to add to the anime for reasons I can't possibly fathom. The 2nd season was kind of a letdown for me anyway, but that guy almost single-handedly ruined it. Thank God he never appeared again after that.