Tetsuo Takeda ( manga ) Tetsuo Takeda ( 武田鉄男 , " Takeda Tetsuo " ) is one of the main supporting characters in " Yu - Gi - Oh ! ZEXAL " . He is one of Yuma Tsukumo ' s friends and is a Duelist . Biography . Tetsuo is part of Yuma ' s circle of friends , together with Kotori , Cathy and Takashi . At school , when Yuma kept challenging himself with impossible tasks with his " kattobingu " spirit , Tetsuo usually made fun of him , while Kotori was always worried . Yuma used to Duel Tetsuo very often ; however , he had yet to beat him . One day , Kotori and Yuma found Tetsuo has been forced to Duel by Shark , and after being defeated , he took Tetsuo ' s Deck . Yuma confronted Shark , but Shark took his pendant and broke it . Enraged , Yuma challenged him to a Duel . Shark accepted , and said that they will Duel on Sunday , in the train station . Yuma was searching for the other half of his broken pendant until it was late , Tetsuo appeared and told Yuma not to go , as he would never be able to win , which was a problem of his . Yuma declined , saying that that ' s already a problem of his as well , as Shark broke his most important thing . Tetsuo gave Yuma the other half of the pendant , saying that he found it accidentally . However , it can be clearly seen that Tetsuo was searching for it as well , judging by its hands . At Sunday , Kotori and Tetsuo watched the Duel to cheer Yuma on . During the Duel , as Astral appeared to Yuma , Kotori worried about him talking " to himself " . Yuma then asked if she and Tetsuo couldn ' t see Astral , and they said they couldn ' t . when Yuma defeated Shark , Kotori and Tetsuo congratulated him . After Yuma ' s loss to Kaito Tenjo , Tetsuo , Takashi , Cathy , Kotori and Tokunosuke formed the Numbers Club in order to help Yuma . Later , the Numbers Club , Yuma and Astral , went to the Heartland Theme Park to find " Number s " . After their escape from the park , Yuma and the members of the Numbers Club gathered in Cathy ' s house . Tetsuo asked Cathy what she wanted to show them . She pressed a cat paw - like button , which opened a door leading to a big room , with many researchers and big computers . Cathy explained that as an apology for the trouble she caused with Cologne , the Numbers Club ' s headquarters would be established there , where they could look up mysterious phenomenons happening throughout the world , and therefore , locate the " Numbers " . Yuma told the Numbers Club that Astral told him that now he got three " Numbers " , some of his memories have returned . Yuma asked Astral what he could remember , and Astral said his enemy was Dr . Faker , who planned to use the hidden powers of the " Numbers " to destroy the Astral World ; However , it is linked to this world . So , if the Astral World dies , this one will die as well . The Numbers Club then decided to save the world from Dr . Faker . The Numbers Club then started helping Yuma , wearing new super hero - like outfits . Another day , the Numbers Club gathered at Cathy ' s mansion , when a big monitor detected a huge source of energy coming from a Duel involving a " Number " . Tetsuo rushed there and found Eviluder , a Number Hunter . Meanwhile , Kotori called Yuma , who was sleeping at home , and told him about Tetsuo . They immediately went after him , but when they arrived , they found Tetsuo laying on the ground , injured . Tetsuo gave his Deck to Yuma in order to help him improve his Deck . Yuma took the cards and did so . After that , Tetsuo was hospitalized . Deck . The only known cards in Tetsuo ' s Deck are " Tin Archduke " and " Tin Balloons s " . He included the latter card in his Deck when he gave it to Yuma , who used the card against Eviluder .