For lack of actual books and not manga, and I was going to say this anyways, Stephen King. His stories are gripping, relentless, and shock to your core. They may not be scary in some cases, but they are gripping and chilling to the very bone. Don't read them at night unless you've got nerve. I've read over 15 books by him, including IT, Misery, Cujo, Carrie, The Shining, Firestarter, The Stand, The Green Mile, and am currently double-reading both Rose Madder and Duma Key. I can't reccommend him enough, to be honest. So long as you like the genre.