Koji Nagumo ( manga ) Koji " the Spider " Nagumo is a character in the " Yu - Gi - Oh ! " manga . He is a student and gamer in Domino High School . Kyoji Yagumo in the " Yu - Gi - Oh ! ZEXAL " manga may be inspired by this character . The characters have similar names and are linked to spiders . Biography . " Monster Fighter " . Nagumo attempted to monopolize on the popularity of " Monster Fighter " , while it was popular and shops had limited supply . He would steal equipment from others and sell them at an inflated price of ¥30 , 000 ( about US $ 300 at the time ) . He presented himself as a keen gamer to Yugi Mutou , inviting him to play " Monster Fighter " , while they were at school . However after they began , he announced his " house rule " , in which the loser must surrendered their gun and figure to the winner . While Yugi was shocked by this , Nagumo hit him and took his gun and monster , Alti . Dark Yugi approached Nagumo , at the gym , where he had been selling " Monster Fighter " equipment . He challenged Nagumo and his Wild Spider to a match , using Killer Emaada , which he had borrowed from Katsuya Jonouchi . Dark Yugi warned Nagumo that their the game would be a Shadow Game . In the first round , Nagumo attempted to punch Yugi . However this distracted him enough for Dark Yugi to knock out Wild Spider . The nature of the Shadow Game , caused Nagumo to suffer the pain inflicted on his monster , resulting in his face being cracked . In the second set , Nagumo cheated by kicking Dark Yugi in the side , allowing Wild Spider to land three intense blows to Killer Emaada torso , winning the set . Enraged , Dark Yugi intensified the game , raising the " shadow mode " to level three . When Nagumo tried to cheat again in the third set , but his legs were held down by all of his stolen monsters and his own Wild Spider . Meanwhile the monster on his gun had been replaced by a twisted caricature of his soul , composed of Wild Spider ' s body with his Nagumo ' s face and arms . Dark Yugi then dealt the killing blow , piercing the representation of Nagumo ' s soul , and leaving the real Nagumo unconscious . . Battle City . Nagumo was unhappy with the card he had won through the ante rule , after one of his Duels . He demanded that his opponent give something of equal value to his card , " Hyozanryu " or ¥100 , 000 ( about US $ 900 at the time ) . However , Mokuba Kaiba appeared and calls a foul for changing the ante and wagering money . Nagumo threatened Mokuba and told him not to mess with his rules . However Seto Kaiba arrived and warned Namugo that insulting Mokuba is insulting Kaiba Corporation . Kaiba tore up the " Hyozanryu " card , saying Nagumo was going to lose it anyway . He challenged him to a Duel , anteing a briefcase of rare cards and " The God of the Obelisk " . He allowed Koji to use the cards from the briefcase in the Duel , to compensate for " Hyozanryu " , but said he would take them back after he wins . Despite his newly empowered deck , Nagumo suffered a devastating defeat as Kaiba unleashed " Obelisk " . Kaiba took Nagumo ' s Puzzle Cards , leaving him traumatized by the overwhelming power of " Obelisk " , and screaming in terror as he relived the image of the God crushing him . Gaming items . For " Monster Fighter " , Koji used the monster " Wild Spider " . He also had a number of stolen fighters , which he sold . The only card seen in Koji ' s " Duel Monsters " Deck was " Hyozanryu " .