Kiyoshi Yoshioka

Yoshioka is hardened, amoral and remarkably calm around violence. Hatanaka's aggressive behavior barely surprises him, and he joins the attack on the Onion Alien without much concern for what the creature actually is.

He can nevertheless recognize when events have gone too far. After the younger Onion Alien is brutally killed, Yoshioka remarks that the group may have become carried away.

His composure persists even under severe injury, allowing him to continue fighting when most untrained civilians would be incapacitated by panic.

Yoshioka is an ordinary human but has experience with firearms through his criminal background.

Unlike most participants, he possesses a conventional handgun when reconstructed in the Gantz room. He uses both ordinary weaponry and the unfamiliar Gantz equipment during the Onion Alien mission.

He does not wear the Gantz suit, leaving him without enhanced durability when the adult target retaliates.

Yoshioka and Hatanaka are introduced among the first participants Kurono and Katou encounter. Their Yakuza background makes them immediately more comfortable with violence than the teenage protagonists.

Yoshioka joins the pursuit of the Onion Alien and participates in the brutal attack on the smaller target.

When the adult Onion Alien arrives, it tears off Yoshioka's arm and opens his abdomen. Despite his injuries, he fires his conventional handgun at the alien before collapsing from blood loss.

Hiroshi Hatanaka is Yoshioka's criminal partner and enters Gantz alongside him after the pair are involved in a shootout.

Kei Kishimoto becomes the target of Hiroshi Hatanaka's predatory behavior shortly after she materializes, while Yoshioka largely treats his partner's actions with amusement.

Kei Kurono and Masaru Katou enter the same first Gantz mission as Yoshioka.

Takashi Inamori fights alongside Yoshioka and the other newcomers during the Onion Alien hunt.