Yes, yes, I get it. You hate Masao. You really, REALLY hate Masao. You think he's scum. You think he's a shallow straw loser or a joke, regardless of his depth of character. You think he's worse than Megumi, the gal who BLATANTLY ABUSES HIM whenever they interact (whether verbally, physically, or both). You think he has no business even being in the series much less taking up as much screen time as he does.
But I ask you: what do you expect him to do to win you over? What is it that makes him so much worse than the rest of the cast? You say he doesn't grow or change throughout the series...and Megumi (or for that matter, Natsuno/Toru/Sunako/Nao/fill-in-the-blank) does? You say he complains too much? Yes, because God forbid a mentally-disturbed seventeen-year-old boy with zero social skills whom everyone and their mother resents and rejects ever act upset or complain about his lousy deal in life! I grant that he can be creepy, and a jerk. But did you ever consider that maybe he can't help it? We know he has no social skills, and there's quite a lot of evidence suggesting he might actually have a disability. Yes he's a jerk, but I really don't think it's entirely his fault he's a jerk. And in any case, is he really any worse than someone like Megumi (who deliberately and consciously kills and torments people for fun) or Toru (who attempts to force Ritsuko to kill her friend and colleague) or Nao (who murdered her own husband, son, and adoptive parents)? It's not like we ever see him murder anyone, or really behave in any more of a blatantly evil fashion than many other characters.
And just to forestall the inevitable question, I'm not saying any of this necessarily makes him any less of a jerk, or any less creepy. I'm not necessarily advocating letting him off the hook, because there are things he says and does that legitimately go to far. But (and this is a crucial point) if you are the kind of person who will excuse or defend assholish behavior in someone like Megumi or Natsuno, then you should be. Because I honestly cannot believe that a socially-maladjusted teenage boy who seems completely unaware of the effect he has on people could ever be worse than some other teens who know exactly what their effect on other people is, and either don't care or revel in it. And if you're the kind of person who would...well, that says more about you than about the "Shiki" cast!