Sci-fi anime about a group of people who are resurrected from their deaths to fight alien criminals on Earth. The last thing Kei remembers is the train running over his own body. Now he is in a room filled with strangers, all resurrected by the featureless black sphere known only as Gantz. But their reprieve from death may only be temporary, for unless they undertake the brutal missions that the Gantz assigns, none of them will live long enough to leave the room. Is it a game? A nightmare? All Kei knows is that if they fail, they will die again...