Gantz

Kei Kurono is a cynical high school student who keeps to himself, tired of the cruelty people are capable of. One day at the subway station, his classmate Masaru Katou jumps onto the tracks to save a drunk man who has fallen. On impulse, Kei follows him. They manage to pull the man to safety, but both boys are struck and killed by the oncoming train.

Instead of dying, Kei and Masaru wake up in an apartment full of strangers, all of whom have recently died. In the center of the room is a large black sphere called Gantz. It gives them high-tech suits and strange weapons, then sends them out to hunt and kill bizarre alien creatures hidden on Earth.

Each mission is brutal and often deadly. Survivors are returned to the apartment and awarded points based on their performance. Kei is allowed to resume his daily life, but at any moment Gantz can summon him back for another mission. As the targets grow more dangerous and the rules more twisted, Kei must decide what he is willing to do to survive.