Gantz

The personality expressed through the Tokyo sphere is mocking, crude and indifferent to the hunters' suffering. Mission profiles frequently assign insulting nicknames, and scoring screens can ridicule participants for poor performance.

Whether those behaviors represent the personality of the man inside the sphere or merely the programming of the system is initially unclear. The interface rarely explains itself voluntarily and provides only the information necessary to begin a mission.

Gantz shows no conventional empathy toward participants. People are treated as hunters, targets and stored data rather than individuals whose deaths require explanation or mourning.

The Gantz system possesses technology far beyond contemporary human capabilities. It can reconstruct people from stored information, transport them over distance, erase memories and deploy advanced equipment.

Its standard arsenal includes form-fitting suits that dramatically enhance strength, speed, jumping ability and durability; X-Guns and X-Shotguns; Y-Guns capable of restraining and transferring targets; controllers with radar and cloaking functions; extendable swords; and specialized vehicles.

Players earn points by defeating mission targets. At 100 points, the system presents three major options: leave the game with memories erased, receive a more powerful weapon, or restore a person preserved in Gantz's memory.

Gantz begins as the central mystery controlling Kurono, Katou and the other participants. It gives them targets without meaningful context and turns survival into a scoring system, leaving the hunters to determine for themselves whether its rules deserve obedience.

The sphere's ability to reconstruct people becomes increasingly important as the team learns that death within the game need not always be permanent. Its technology also expands the scale of what the hunters can accomplish as stronger equipment becomes available.

The later story reveals that the black spheres are human-built systems manufactured using advanced technological information transmitted to Earth by an alien civilization preparing humanity for another extraterrestrial species. The person inside each sphere is a duplicated human used as an interface rather than the true creator of the technology.

Kei Kurono begins as one of Gantz's unwilling hunters and eventually becomes one of the Tokyo team's most successful participants. The system initially assigns Kei Kurono insulting labels before increasingly identifying him by name.

Masaru Katou repeatedly challenges the assumptions built into Gantz's missions by attempting to protect both teammates and targets rather than killing automatically.

Joichiro Nishi has spent more than a year studying the system by the beginning of the series and understands many of its rules before the other Tokyo participants.

Shion Izumi has an unusually strong attachment to the game. After previously earning his freedom and losing his memories, he is drawn back toward Gantz and commits the Shinjuku massacre to re-enter it.