Hey...
Have you tried School Days....It was very surprsing at the end.
Next, you want shocking and violent ??
Go and see Higurashi no Naku Koro ni (1st season) and
Higurashi no Naku Koro ni Kai (2nd season)
Then, there is Murder Princess. It is very good and bloody. I almost fell out my chair when watching it.
Hope this help