Gantz: Complete Collection (2004)

He thought he was dead. The last thing Kei remembers is the train running over his own body. But now he is in a room filled with strangers, all resurrected by a strange, featureless black sphere known only as the Gantz. Caught in a strange realm between life and death, Kei and the others must undertake brutal missions that the Gantz assigns. Otherwise, none of them wi...