Gantz Omnibus - vol. 1

Former Tokyo schoolmates Kai and Masaru are struck dead by a speeding train, but a split second later they're alive, trapped in a room with other reanimated strangers and an ominous black sphere that soon flashes a dire message: ALL OF YOUR OLD LIVES ARE GONE. I WILL DECIDE HOW TO USE YOUR NEW LIVES. The orb supplies them with high-tech weapons and places them in a strange televised game to hunt a bizarre alien, but the team soon discover that the game is deadly serious... and the dead can still die!