The anime and manga series Gantz features a large number of fictional characters created by Hiroya Oku. The series takes place in a modern Japan, in which several creatures known as aliens start attacking citizens.
The series starts with the teenager Kei Kurono, who dies in a train accident along with his childhood friend Masaru Kato. Suddenly, they appear in an apartment from Tokyo along with several people who have recently died. A black sphere named Gantz revives them and then it sends them messages, telling them they have to kill aliens if they want to live. All the participants are given powerful weapons such as guns, and black bodysuits that increase their strength. As the characters participate in the game, they start discovering more things related to Gantz such as what happens when they defeat several aliens, and why Gantz holds the game.
Names are in Western order, with the given name before the surname (family name).
When creating the chapters from the manga, the author Hiroya Oku first makes a draft of the pages. He then creates 3D models of the characters and backgrounds on his computers. Once done, Oku scans the characters draws he made in the 3D models, and the backgrounds are reduced to lines. Finally, he then adds tone to the pages and colors them, and starts adding sound effects as well as dialogues.
Kei Kurono (玄野 計 Kurono Kei?) is one of the two main protagonists of the series. Kei is a 10th grader who is summoned by Gantz, along with his childhood friend Masaru Kato, after being hit by a subway train in an effort to help a hobo who passes out on the tracks. In the beginning, he is a rather selfish character, with a penchant for sexual perversity, who often ends up being the reluctant hero. However, after Kato dies in the third mission, Kei starts taking care of other people as well, and he starts to avoid casualties amongst Gantz team members. His innate skills and physical prowess eventually make him a hero to most of the other members. During missions, Kei often uses unconventional tactics to great effect. He lives alone in an apartment complex, as he was not on good terms with his family. After reviving some of his former friends, Kei leaves the game due to a request from his comrades. The vampires group searches and eventually finds Kei, killing him. After the first mission of Phase 2, he is revived by Masaru Kato but remembers nothing beyond his choice to leave after the Oni Mission. After the failed Italian mission, Gantz revives an additional copy of Kurono at Reika's request, unknown to the others. After meeting the original Kurono, he decides to live with Reika. Oku developed Kurono's character with the idea that the readers from the manga could identify themselves with him. However, he was also created to "make a synthesis of the basic conditions for a work of entertainment". His Japanese voice actors are Daisuke Namikawa in the anime and Yūki Kaji in Gantz: O. His English voice actor is Christopher Ayres. His live-action actor is Kazunari Ninomiya.