Kouki Inaba was a victim of Izumi Shion's Shinjuku massacre, and later a member of the Tokyo Gantz team.
Inaba is a quite tall individual, with shaggy hair almost reaching his shoulders. When not participating in the missions, he is regularly shown wearing baseball caps. Upon his first introduction into the game, he is shown to have a soul patch, but later on, he is shown to have it on and off.
In entering the Gantz game, and from the dinosaur alien mission onward until the beginning of his foray into the Italian mission, Inaba is shown to be usually quite cowardly and somewhat inept, and is frequently shown hiding from the aliens they fight. In the dinosaur alien mission, he takes over for Reika and is given her gun, but he does not use it all or is unsuccessful with shooting it, and receives 0 points. Despite caring for Reika, he does not step up to help her when she is being crushed to death by the Oni Alien due to his fear, and it is up to Kurono to save her. To hide his emotions, Inaba will sometimes feign a cool head in these situations, such as against the Nuraihayon alien, suggesting if the team works together they can defeat it.
Often frustrated by his own lack of success, Inaba is shown at times to deeply resent Kurono, since Reika loves Kurono, and not him. During the Tae Kojima mission, he is the one who physically attacks Kurono himself, citing the reason that he will never accept Kurono as his leader, but, later upon witnessing Kurono's exploits during the Oni Alien mission, he begins to believe in Kurono. Even so, afterwards, he seems to hold a somewhat low opinion of him, even calling him a "high school punk", in an attempt to debase Kurono in front of Reika.
As hinted by his outburst before the Italian mission, Inaba felt deeply alone and isolated, feeling there is no God with compassion to save those from dying horribly in the missions, and believing that nobody truly cared about him. Upon witnessing Suzuki's death, in his attempt to save him, Inaba reminisces that Suzuki had been the only one who actually cared for him all this time, and that he had never actually been alone. With this insight, Inaba gains the will and inspiration to fight and survive, showing bravery and skill, defeating several of the powerful aliens, and even showing calmness when faced with a sub-boss, who he is able to take down, albeit with the loss of his left arm.
Inaba's occupation is a designer. He and his girlfriend were shopping in the stores along Shinjuku street, before they were caught in the massacre Izumi was committing. Upon being killed, Inaba ends up in the Gantz game.
Kouki Inaba was shopping with his girlfriend on Shinjuku street, before being caught up in the massacre. Upon being killed, he found himself in the Gantz room, before being deployed, along with the others on the dinosaur alien mission. During the mission, he talks to Reika, joking with her about her Gantz suit. When he reveals how he died, Reika seems somewhat put-off by his apparent lack of emotion on his face about the state of his girlfriend, though he vocally expresses his hope that she's alright. When the raptors attack, he takes Reika's gun from Kurono, though he does not use it, or at least he is not able to successfully kill any of the dinosaurs.
Inaba is not shown during the Ring Alien mission, but he receives 0 points, indicating he killed no aliens.
During the Tae Kojima mission, he sides with Izumi, and helps with the attack upon Kurono. Upon cornering Kurono, he is the one who spearheads the attempt to take him down, and Inaba physically assaults him, which draws Tae Kojima out to help her boyfriend, allowing Izumi to successfully kill her. Inaba also states he will never accept Kurono as his leader.
During the Oni Alien mission, Inaba teams up with some of the rapist hunters who have arrived in the room, and they confront the Oni Alien boss. Upon his group members' deaths, he runs away, when he is confronted by an alien impersonating Reika. He has intercourse with the alien in public, when the real Reika arrives, and the alien flees. While Reika pursues the alien, he waits with two surviving new hunters. Once Reika comes back with Kurono, Inaba suspects Kurono, who is revealed to be the same imposter alien again. They all shoot at it, before it invades two of the hunter's bodies, and then assumes an elephant form. Kurono arrives to kill it. Inaba then goes along with the others to confront the Oni Alien, though he simply hides from it the whole time, while cheering on Kurono and futilely fails to do anything to help Reika when she is being crushed by the Oni alien boss. Upon entering the Gantz room, he is shown crying, though he receives 10 points, and laments how he's almost as useless as Hoi Hoi and Takeshi.
During the Nuraihayon mission, Inaba asserts they can defeat the alien if they work together, but after the group consensus of fleeing, he attempts to do so, but is severly injured. After the mission, he tries to persuade Reika to choose him instead of Kurono, but she apologizes and refuses.
Before the Italian mission, Inaba gets a premonition of his own death, and states that they will all die, that there is no God, and he feels as if it's the "devil's playground" on Earth. He flees from the aliens in the mission, and is cornered, with him surrendering. They rip off two of his fingers of his left hand, and, before they are able to harm him further, Suzuki arrives to save him, imploring Inaba to fight on, until the very end. Suzuki is swiflty killed, by having all his limbs ripped off. As Inaba shivers and moans, he looks on at Suzuki's body; crying, he realizes that Suzuki had always truly cared about him. Receiving the inspiration to fight on, he strikes back, and successfully kills several aliens, while losing an ear and eye. Recognizing what Suzuki had done for him, Inaba is then confronted by a sub-boss, which he successfully kills while losing his left arm. Kurono and Kato then run to his location, to see Inaba, who simply states Kurono's name. The boss alien then steps on Inaba, killing him instantly
Abilities and Skills
Through out much of his appearance on the Gantz team, Inaba was unable to muster the courage to fight, yet during the Italian mission he showed impressive combat skills with the Gantz gun and was able to kill several aliens and even a sub-boss.
Inaba had a girlfriend before he died and appeared in the Gantz room, yet when Reika asks him about her, he does not seem visibly affected by the fact that she might have died in the massacre also. This could indicate he really didn't care about her.
Though he does not train with Kurono and the others, he is shown to regret this during the Oni Alien mission.
Inaba was mentioned in the final chapter as one of their many companions who died during the events of the series.
Though believing only Suzuki cared about him, Kurono and Kato both grieve for him after his death.