- "Just so you know, this is not mercy! I just don't want to be the like of you!"
—Tatta in the manga Chapter 28
Kōdai Tatta is a character first appears in the Beach arc. A rather decent man whose real specialty is his knowledge of automobiles.
Tatta's father ran an unprofitable automobile repairing garage and died leaving the debt for his wife and son. Tatta dropped from high school when he was 18 years old because he wanted to become a stand-up comedian. In order to afford his living, he applied 3 part-time jobs at once, but his performance was not recognized by producer or audience, eventually Tatta fell prey to pyramid scheme for quick cash.
Because of his knowledge of automobiles, he is in charged of fuel filling in the Beach with another resident he befriends. When Boshiya's corpse is found by them, both fuel staffers are ordered to keep quiet and pretend that he dies in the game. When Witch-Hunt commences and Niragi provokes the crowd to kill Usagi and Asahi, the wrong culprits, Tatta's friend loudly accuses the women of Boshiya's murder. This revelation causes his life in Last Boss' hand, Aguni then orders his underlings to kill all residents indiscriminately. The crowd runs away from Aguni's men in despair, the shocked Tatta is carried away by Usagi along with Asahi. Tatta helps Usagi to bait a martial member to get Arisu's whereabouts and his gun. Usagi discards the magazine because she only needs the gun to frighten the martial members, but Tatta secretly keeps it to himself. When the game is cleared and the whole resort is about to collapse from fire, Tatta points the gun at the wasted Last Boss who has been knocked out by Kuina. Tatta is unable to pull the trigger, knowing his enemy wishes to die.
During the intermission, Tatta regrets masturbating to Kuina after the trans woman reveals her true sexuality.
Just before the second "face card" stage is about to begin, Tatta gets few cars functional for Arisu and An's group to escape from the King of Spades' initial attack separately. Tatta travels with Arisu, Usagi and Kuina for the King of Clubs arena, unwillingly joined by Niragi whose skin was burnt by Chishiya during Witch-Hunt. Tatta is given the role of "gatekeeper" for their team against the citizens' team because that is a relatively safe role requiring the least effort. After Tatta's team is put in an irreversible disadvantage because of a suicidal ambush of the opposite team, Tatta asks Arisu to amputate his arm to remove the game bracelet from him. Even though Arisu has successfully turned the table using Tatta's bracelet and won the game, Tatta dies after blood loss. His body is buried in a seaside park.