Gantz
Tags: violence

Plot synopsis:
A pair of high school students, Kei Kurono and Masaru Kato, are hit by a subway train in an attempt to save the life of a drunk homeless man who had fallen onto the tracks. Following their deaths, Kurono and Kato find themselves transported to the interior of an unfurnished Tokyo apartment, where they meet Joichiro Nishi, a Gantz veteran, and other clueless participants. The pair soon realizes that they are not allowed to leave the apartment. At one end of the room there is a large black sphere known as "Gantz".
After some time in the room, the Gantz sphere opens up, revealing a bald naked man with a breathing mask and wires attached to his head, and various weapons for them to use. These include the custom fitting black suits which give them super-human strength, speed, stamina and damage resistance, a controller which acts as a radar and stealth unit, X-gun, X-Shotgun, Y-Gun. Later on the series the Gantz sword, Gantz Bike are made available as well as much more powerful weapons are awarded in the 100 point menu.
When the Gantz sphere opens, green text appears on its surface, informing those present that their "lives have ended and now belong to him". A picture and brief information is shown of some of the Gantz' targets; Gantz orders them to go and kill them. Except for a single mission, all the targets are aliens living on Earth, which take on a wide variety of forms. During the mission, normal people cannot see the players or the aliens. Gantz transports them to the area of the mission, and they cannot leave or return until all the enemies have been killed, or the time limit has run out. If they survive a successful mission, each individual is awarded points for the aliens they have killed. Once a participant has scored 100 points, a "100 point menu" will appear. The menu offers three options:
Option 1: The participant can return to their normal life, never having to be summoned by Gantz again. As a price, their memories of Gantz and the missions will be erased.
Option 2: The participant obtains a unique and extremely-powerful weapon.
Option 3: The participant can revive someone who has died during a mission from Gantz' memory.
After a mission has been completed, points are tallied up, the participants are allowed to leave and do as they see fit until their next mission, with the exception of talking about Gantz which would lead to their heads exploding. During Kurono and Kato's third mission, all the participants including Kato are killed, however Kato kills the last boss giving Kurono a chance to survive. Kurono survives the third mission bleeding on the floor with his limbs cut apart. After the third mission Kurono starts to change inside adopting a hero, leader complex similar to Kato. As the series continues, Kurono participates with the objective of reviving his deceased friends with the 100 point reward option. A new team of Gantz players is assembled, which Kurono leads, as the most experienced veteran and one of the best fighters. In the Oni mission it is shown that with Kurono's "will to live" he becomes the most ferocious Gantz hunter in the team. Through his interactions with the other members of the team and his life or death battles, Kurono gradually grows into a responsible leader. After the Oni mission Kato is revived by Kurono, and soon after Kurono meets his demise against the vampires. As the series goes on, the rules of the missions change; they can now be seen by regular people, the aliens they encounter are increasingly more powerful and dangerous, and they participate in a mission with another Gantz team from Osaka. Kato becomes the center of attention in the manga and his quest to revive Kurono. In a desperate attempt to revive his best friend, Kato fights the one hundred point alien Nurarihyon which obliterates both Osaka and Kurono's team. At the end of the mission, similar to the first time Kato died, he defeats arguably the strongest alien in the series and is laid bleeding on the floor. The series depicts both the missions and Kurono's regular life, as well as the daily lives of other Gantz players (to a lesser extent).
After several missions, an old participant named Nishi, who knows more than the others about how Gantz works, shows them a "catastrophe countdown" on the Gantz sphere which the other players were unaware of. The countdown reveals that there is one week left until some unknown "catastrophe." At the end of that week, a massive alien force invades the Earth and begins exterminating the human race, while Kurono and his companions try their best to make use of Gantz' advanced technology and weaponry in defense. At the end, Nishi and Kurono are depicted to be similar, both of whom were despised by their family and were sinister; however, unlike Nishi, Kurono has a reason to live. Nishi, in the chapter "The Great Escape", is left for dead by Kurono, vowing vengeance against him and crying out for Gantz and mother for help. It is hinted that Nishi died, but his death seems to be unclear. The Japanese also learn of the existence of Gantz teams all around the world. After a long battle, the humans manage to stop the alien invasion and soon after, it is revealed that it was another, highly advanced alien species that provided mankind with the means to defend itself against the invaders, for reasons they refuse to reveal and calls it a whim. In a desperate last effort, the leader of the alien forces, Eeva, challenges the whole human race, promising to exterminate every inhabitant by himself by crashing their mother ship, killing both races if Kurono does not come to their mother ship to fight him. Prior to this announcement Eeva completely dominates all Gantz teams in his vicinity by killing all the hunters, giving the human race a sense of their mortality. The world calls on Kurono, which is broadcast to the entire world, and, with a revived Kato's help, Kurono bets all his chance of winning and saving the human race on himself. Kurono manages to defeat Eeva, thus preventing the alien mothership from destroying Earth. The series ends with Kurono and Kato returning safely to Earth and being greeted as heroes.