Jun autistic? and thoughts on Kim

So... is Jun supposed to be autistic or something of the sort? I am genuinely asking here.
He's not speaking at all and acting really weird all the time. It's the typical behavior of a child being wrapped in it's own world, only very, very intensified.

I think I've seen similar portrayals of children in other Korean movies. Is this supposed to be normal behavior for a child that is having a tough time?

I'm just baffled and want to know whether this is normal in that culture, or the movie hyperbolized it, or maybe he was supposed to be portrayed as autistic/suffering from a condition.


Also, felt sorry for Kim for having to go through the *beep* he did. He clearly aimed his feelings are the wrong person at a wrong time.