American horror comics are cool, no doubt, but if you really want the hardcore stuff, you have to step across the pond to Japan. There's a veritable army of awesome artists lovingly creating dark tales of depravity and gore. One of the masters is Kazuo Umezu, and his most disturbing work is The Drifting Classroom. A strange explosion at a Tokyo elementary school whisks the kids and teachers away to a post-apocalyptic future infested with terrifying mutants and deadly diseases, and most of them don't survive. It's insanely grim and features tons of cute kids dying in tremendously unpleasant ways.