Yeah their are few Japanese Drama's that deal with autism.
The Things You Taught Me (also known as From the Heart) it's okay but it does start off slow. Mayuko is the main character she has a talent for predicting weather and she actually get's a real job doing it the drama is mostly about the relationship between her and her psychiatrist.
I've only seen a few episodes of
Boku No Aruku Michi I dropped and haven't had the time to start watching it again. It seems okay but I don't know how it ends.
Pure is another one although I'm not sure if the main character has autism or not but she also a talented artist her name is Yuka. It's basically about a magazine trying to exploit her and relationship she has with a man named Toru who works as a reporter for the magazine.
From The Heart http://mydramalist.com/6025-the-things-you-taught-me
The Road I Choose to Walk
http://mydramalist.com/2505-boku-no-aruku-michi
Pure http://mydramalist.com/4341-pure
But their are several others I've seen I just can't remember the names of the drama's. Hopefully someone else will post them. Have fun hopefully you like at least one of the drama's I recommended.