Looking for a messed up and disturbing anime?

I've already seen Elfen lied and School days, two which seem to be mentioned often on the topic of disturbing anime. I thought Elfen lied was mainly Gorey and sad, rather than disturbing and I found school days a little hard to take seriously. I actually kinda enjoyed the ending, because the guy had become such a jerk. The rest of it was just pretty miserable. Can anyone think of any others?