This is a pretty new manga that has proven itself worthy of it's own thread with the most recent chapter that has been released, read and you'll find out. Any of you interested in stuff like Gantz, Battle Royale, and other psychological screwers will love this series. Here's a
link to manga update's page.
Don't let the shounen genre scare you away. The only reason why it is labeled as a shounen is because it's serialized by Shonen Ace. If anything, it has much more of a seinen feel to it. Of course it does consist of a few shounen elements, but that doesn't hinder the story any bit.
Anyway, on with the discussion... (If you read the most recent chapter you can look in the spoiler)