A couple of high school pupils, Masaru Kato and Kei Kurono, are hit with a subway train in a effort to save the life span of a drunk homeless guy who'd fallen onto the tracks. Following their deaths, Kato and Kurono find themselves transported to the inside of an unfurnished Tokyo flat, where they meet with a Gantz expert Joichiro Nishi, as well as other clueless players. The pair soon understands that they're prohibited to depart the flat. At one end of the room there's a sizable black sphere called "Gantz".
After some time in the area, the Gantz world opens up, showing wires attached to his head and a hairless nude guy using a breathing mask, and different weapons to allow them to use. Included in these are the custom fitting black suits which give them superhuman speed, strength, stamina and damage resistance, a control which functions as a stealth and radar unit, Xgun, X Shotgun, Y-Firearm. Later on the show the Gantz sword, Gantz Bike are manufactured much more powerful at the same time as accessible weapons are given in the 100 point menu.
Brief info and a picture is revealed of a few of the Gantz' objectives; Gantz orders them to go and kill them. Except for one assignment, every one of the goals are aliens living on Earth, which take on a wide selection of types. During the mission, individuals that are ordinary cannot view the extraterrestrial beings or the players. Them transport to the part of the assignment, and they can't return or leave until all of the enemies are killed, or the time limit has run out. Each person is given points for the aliens they've killed, when they survive an effective mission. The menu offers three choices:
The participant can go back to their regular life, never having to be summoned by Gantz again. As a cost, their memories of the assignments as well as Gantz will be erased.
The participant gets a unique and incredibly-powerful weapon.
The participant can restore a person that has died during a mission from Gantz' recollection.
Points are tallied up following an assignment was finished, do and the players are permitted to leave as they see fit until their next mission, together with the exception of talking about Gantz which would lead with their heads bursting. During the third mission of Kato and Kurono, every one of the participants including Kato are killed, however the last leader giving a chance to live to Kurono is killed by Kato. Kurono survives the third mission bleeding on the ground along with his limbs cut. Following the next assignment inside embracing a hero, leader complex similar to Kato Kurono begins to transform. Kurono participates together with the goal of restoring his dead friends using the 100 point compensation choice as the show continues. A fresh team of Gantz players is gathered, which Kurono leads, as among the greatest combatants plus the most seasoned veteran. Through his interactions with all the other members of his life or death conflicts and the team, Kurono slowly develops into a leader that is responsible. Following the Oni assignment Kurono revives Kato, and shortly after Kurono meets his death from the vampires. As the show continues, the rules of the assignments change; regular folks can now see them, the aliens they face are increasingly more strong and dangerous, plus they participate in a mission with another Gantz team from Osaka. Kato becomes the center of his search to restore Kurono and attention in the manga. By the end of the assignment, Kato that is just like the initial time expired, he gets the better of arguably the most powerful alien in the show and is set bleeding on the ground going to expire.
After several assignments, an old player named Nishi, who understands more in relation to the others about how Gantz works, reveals them a "catastrophe countdown" on the Gantz world that the other players were unaware of. By the end of the week, the Earth is invaded by a huge alien force and starts exterminating the human race, while their utmost tries to use Gantz' innovative technology and weapons in defense. It's suggested that Nishi expired, but his departure seems to not be clear. In his area Eeva totally controls all Gantz teams prior to the statement by killing most of the hunters, giving an expression of the mortality to the human race. Kurono that will be air to the whole world is called on by the world, and having the help of a revived Kato, Kurono gambles all his potential for winning and saving the human race on himself. Kurono manages to overcome the alien mothership stops from destroying Earth. The collection finishes with Kato and Kurono being greeted as heroes and returning safely to Earth.