Shiki disturbing? Firlefanz!
I actually had a good laugh at the scenes were
Not because I usually laugh at such cruel scenes but because I simply was not a fan of the series and couldn't take the story seriously.
Shigurui was indeed disturbing, and they didn't even animate most of the 'worst' parts of the manga. It may even be possible to make a second season to do these parts and the ending.