Bronk Stone, known as Tetsuo Takeda (武田鉄男, Takeda Tetsuo) in the manga and Japanese versions, is one of the main supporting characters in Yu-Gi-Oh! ZEXAL. He is one of Yuma Tsukumo's friends and is a Duelist.
Bronk's design is quite unique, as he is drawn in a completely different way to the other characters within ZEXAL. He's usually seen wearing a cap backwards with his hair sticking out of the front and sides.
When in his school attire, he sports a red and white shirt, with a red tie which is the same as Caswell and Yuma's and blue pants strapped with black suspenders which feature round, metal orbs. When in his casual attire, he wears an orange t-shirt with a smiley face on which reveals the bottom of his stomach, much like his school attire does. In the Heartland Academy festival, he wore a "Gogogo Golem" cosplay.
Bronk is quite a competitive and adamant person who takes pleasure in other people's embarrassment, even if it is his own friends; much like the times when he makes Yuma get worked up and challenge events which he can't win, which ends up in Bronk and the other classmates laughing.
He is also a strong-willed person who doesn't like to show his emotions, like when he obtained the broken piece of Yuma's pendant and said he just "came across it", when Shark had clearly kicked it into a small forest near their school (in the English dub, he flatly states that he went looking for it). Despite this, he seems to have friendly rivalry with Yuma, as he tends to be on Yuma's side and though doesn't always believe that he'll be able to turn around his Duels, he supports Yuma most of the time.
Bronk seems to have an incredibly strong will. When Yuma was possessed by Number 96: Dark Mist, he used Yuma's "Number 39: Utopia" to save him, and was quickly able to shake off the corrupting effect that strikes most Numbers users (although probably due to holding Emperor's Key).
He also developed a crush on Rio Kastle not long after meeting her, and this has continued to persist, unlike the initial attractions from the other students.
The 鉄 (Tetsu) in Bronk's Japanese name (Tetsuo) means Iron, and the 男 (O) can be read as Otoko, which means man or guy. So, his name can be read as "The Iron Guy", mirroring his Deck type.
Bronk originally met Yuma after he joined his and Tori's class when they were younger. After Yuma claimed that he would be the Dueling champion, Bronk challenged his statement and despite beating him many times, found Yuma never gives up. Yuma has firey spirit, therefore befriended him.
One morning whilst Yuma was late for school, he ran into Bronk who challenged him to a race. As the two raced, Bronk kicked a Litterbot into Yuma's path, causing him to fall over. Bronk then drives away, cheering at not only winning the race, but Yuma's downfall. Bronk is later spotted by Tori when she and Yuma are wandering around the Heartland Middleschool grounds. She instantly notices that he is Dueling Reginald Kastle, so the two run up just in time to see Bronk get defeated by the Duelist. Reginald then takes Bronk's Deck as he had put it up as an ante, due to the pressure of Reginald and his friends calling Bronk pathetic for not originally agreeing with the terms. After Yuma defends Bronk, Reginald snaps his pendant and throws half of it in the bushes. Yuma went to punch Reginald, but Bronk stopped him as he didn't want him to stoop to his level. The next day, Bronk noticed how depressed Yuma had become without his full pendant, therefore managed to find the second half and gave it to Yuma whilst walking home from school. He then told Yuma to not Duel Reginald, but Yuma argued that he had to for himself, not for Bronk. Bronk then went with Yuma to watch him Duel against Reginald and was shocked at not only Yuma's Dueling, but also at Reginald Summoning "Number 17: Leviathan Dragon" instead of "Submersible Carrier Aero Shark".
As the Duel continued, Yuma continued to baffle Bronk such as claiming that there was a "Dueling ghost", telling him what to do. Furthermore, when Yuma Summons "Number 39: Utopia", Bronk is extra shocked as he had never seen Yuma use such a card and the fact that it was also a "Number". When Yuma defeated Reginald, Bronk cheered along with Tori as he managed to get his Deck back.
After beating Reginald, Bronk was walking home with Yuma and Tori as a virus erupted throughout Heartland City. Which caused the various technology throughout the city such as traffic lights and vending machines to malfunction. Yuma tried to steal drinks from the vending machines, but was picked up and put inside a malfunctioning Litterbot. After arriving at Yuma's house, the group hear Kari Tsukumo scream, to which they all rush to her aid... only to find her sitting in her computer room with a broken computer. The three escape before she took out her anger on them.
One morning at school, Flip, a boy from Bronk's and Tori's elementary school tried to reward Yuma with a "Baby Tiragon" card, which Bronk and Tori kept Yuma from claiming. Bronk told Yuma that it was because Flip was a dark and mischievious person who always causes mayhem. Despite managing to keep Flip away from Yuma at school, they couldn't stop him mailing Yuma the card. After which, Flip began a masterful plan in which singled Yuma out at school, therefore making him alone. Bronk didn't believe that Yuma would do such stuff, for example, making frogs attack Spencer.
To prove Yuma's innocence, Bronk and Tori set out on finding evidence. Tori manages to see that the images of Yuma had been altered due to blurs around the image edges. They then decide to find Spencer to ask him about the events. After visiting his house and running around school, they manage to locate him and find out that Flip hid him and made him take on an enduring task so that no one would find him in time so that he could Duel Yuma and take his "Number 39: Utopia". They then run to the mall to see Yuma defeat Flip, and then befriend him.
When Nelson Andrews, the star of "The Sparrow" visited Heartland City, Bronk decides to see if they can see him along with his friends. After managing to sneak into the studios, Yuma manages to cause the destruction of a large portion of the set, notifying the security of them being there, resulting in Bronk and Tori being kicked out. Bronk then wonders where Yuma went after Fuya rescued him in order to give him his Deck back.
After Yuma manages to find Nelson and challenges him to a Duel, Tori calls Bronk and Mrs. Andrews to go and watch the Duel. After Yuma wins, Bronk celebrates with Tori. On their way home, Tori and Yuma get into an arguement, which amused Bronk whilst Reginald looks on in the background.
One morning, Bronk is discussing Yuma's current winning streak with Tori and says that Yuma's catchphrase of "I'm Feeling the Flow" is meant more for losing, rather than winning. He is then shocked at the clothes Yuma is wearing when he turns up for school. After Yuma's Duel with Cathy, he tries to think who Cathy is, but can't remember as she lurks in the background rather than socialising.
After Yuma's loss with Shark, Bronk turned his back on Yuma for breaking his promise not to use Numbers, which included not wanting to see Yuma and Shark Duel against Scorch and Chills, though Tori talked him into watching. He was present at Yuma's Duel with Shark and their Duel against Scorch and Chills and forgave Yuma for lying.
In episode 13, he informed Yuma, Tori and Caswell of a new Duel plaza that opened up in a neighboring town.
In episode 15, Bronk and Tori informed Yuma of the upcoming World Duel Carnival and accompanied Yuma and Tori on his errand to deliver food to Roku at the Duel Sanctuary. Bronk, later joined by Kari and Haru was present at Yuma's Duel against Kaze, who was under the possession of "Number 12: Crimson Shadow Armor Ninja". When Roku handed Yuma the Duel Sanctuary's Secret Deck, Bronk exclaimed that Yuma should beef his first Deck with the Secret Deck to use for the WDC.
In episode 17, Bronk, Caswell and Tori were discussing to Yuma of different people who were mysteriously hospitalized, and also happened to carry different Numbers. When Yuma refused to talk, Bronk, Caswell, Tori, Flip and Cathy formed the Super Secret Number Card Investigation Club, a group made to solve the Numbers mystery without the help of Yuma. The only leads the Super Secret Number Cards Investigation Club got was Cathy talking about Yuma talking to Astral about Numbers and Kite Tenjo. The search was useless, until Flip found the devious fortune-teller Fortuno, who they thought would lead them to what Number cards are. Fortuno kidnapped the Club, except for Cathy, enticing Yuma to Duel Fortuno. Bronk and the Club witness in horror as Fortuno used the powers of "Number 11: Big Eye" and "Number 16: Shock Master" to put Yuma in a pinch. When Yuma and Astral were feeling hope, Bronk and the Super Secret Number Card Investigation Club watched as they saw Astral for the first time and witnessed the Summoning of "Number C39: Utopia Ray". After Yuma defeated Fortuno, the Super Secret Number Card Investigation Club went to thank Astral for saving them instead of Yuma.
When Yuma recovered Number 96: Dark Mist, Bronk complained that Yuma was just attacking recklessly without listening and they got into a fight, and didn't talk for a couple of days. When they ran into each other, Bronk accidentally knocked the Emperor's Key, causing Astral to lose control over Number 96, who took control of Astral and turned Yuma into his puppet. Yuma gave Bronk his "Number 39: Utopia" so that he can Duel the Wicked Number to rescue him and Astral.
World Duel Carnival
During the day before the World Duel Carnival, Bronk was the most excited out of his friends to have received a Heart Piece. He then mocks Yuma for thinking that they just give them out as anyone from around the world could enter, which would take forever to carry out. After Yuma runs to Heartland to claim a piece, Bronk goes along with him and is shocked at his childish behavior. The night before the tournament, Bronk is seen when Yuma thinks about his friends and their Decks. During the opening ceremonies, Bronk accompanies his friends to see Mr. Heartland explain the rules. He then charges off with Flip, leaving the rest of the gang just before Striker challenges Yuma to a Duel.
During the second day of the World Duel Carnival, Bronk along with Caswell are spotted by Yuma and Tori in a rush. They explain that they had arranged a Duel with Quattro. Yuma attempts to warn Bronk of how Quattro treated Reginald and Rio Kastle, but Bronk ignores this. They then arrive at the location which Yuma finds dark and creepy, but Bronk defends Quattro as a celebrity like him would be swamped with attention in public, whereas in a quiet location, they can enjoy the Duel. After getting his D-Pad signed by his hero, he along with Caswell and Quattro begin a Battle Royal. Throughout the Duel, Quattro compliments Bronk and Caswell on their moves, but it all turns out to be a facade. Despite managing to Summon their Signature cards, Quattro manages to perform a One Turn Kill on both of them with his "Number 15: Gimmick Puppet Giant Grinder", hurting them in the process.
After the Duel, Reginald Kastle appears to Duel Quattro. Bronk takes this opportunity to transport a knocked out Caswell to the Heartland City Hospital in order to recover. He tells Yuma to stay and watch the Duel whilst he and Tori take Caswell to the hospital.
After a few hours of recovering in the hospital, Bronk returned to Yuma to find out that only he is remaining within the tournament. He then went with Yuma and his friends after Yuma's Heart Piece was stolen by a dog. When managing to locate where the dog had gone, Bronk was shocked when a dog, named Roscoe spoke to the gang. After Cathy challenged the dog to a Duel, Bronk watched with Cathy's cat sat on his head. He was even more shocked when the talking dog was revealed to actually be Pip, who was hidden in a device on the dogs back. After Pip defeated Cathy, Bronk was happy that everything was back to normal as Yuma claimed his Heart Piece back.
He and the rest of his friends greeted Yuma, before finding a weak opponent for Yuma. After finding Flip, everyone watched in amazement the Duel between Nistro and Nelson. Like the others, he came to support Yuma as he prepared to Duel Trey. When Yuma lost the will to fight, Bronk expressed his frusteration, saying Yuma was the kind of guy who never gave up. Like the others, he was astonished as he witnessed Astral and Yuma's ZEXAL Change.
World Duel Carnival Semi Finals
He then accompanied Yuma and his friends to the party prepared for the finalists, and like the others is shocked upon seeing Vetrix.  During the day of the semi finals, he along with Yuma's other friends found Yuma sleeping near the entrance gate. After learning Yuma was missing his Heart Piece for the Duel coaster, he along with his friends and Kari helped to bring the Heart piece to Yuma. As he and Caswell witnessed the start of Shark and Quattro's Duel, they said to each other that the girls sitting next to them did not know Quattro's true identity.
World Duel Carnival Finals
After Yuma advanced to the finals, like the others he was happy for his friend. When it was revealed that Yuma's Deck was still in Heartland, he, Tori and Yuma sneaked into Heartland to try getting it back.. As Yuma and Shark Dueled in the finals first match, he and the others wondered what was up with Shark (whom at the moment wasn't putting up too much of a fight). He and the others were shocked upon witnessing Sharks Chaos Number.. Before Yuma's Duel with Vetrix, he told Yuma that he was representing them as Duelists and to not lose. After Vetrix took off his mask, the crowd believed it was a cool vision, however Bronk realized immediatly that was not the case.Following Vetrixs defeat, he was happy like the others, and was then in shock at witnessing Heartland Tower exploded. After Faker's defeat, he alongside the rest of his friends watched the Duel between Yuma and Kite.
Yu-Gi-Oh! ZEXAL ll
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After Fender called Yuma to Duel for the Numbers, Bronk briefly tried to warn Yuma not to come, but was pushed away by Fender. He cheered for Yuma during his Duel against Fender.
He developed a crush on Rio Kastle after she returned to school, and was paired with her in the "Friendship Games." Bronk later was privy to Yuma and Tori's discussion about whether Ray Shadows had attacked Alito, and after Ray realized that Yuma was Dueling Girag alone, Bronk and Tori took Ray to Yuma and Girag. He witnessed the Duel between the three of them, and was shocked at the Barian Sphere Cube and Girag's true form, this being his first time witnessing such a Duel.
While on his way to school on his skateboard, a bunch of crossing ducks appeared. He dragged it on the ground to stop friction, which resulted in him being thrown from the board with the ducks safe. After the ducks crossed, Rio saw that Bronk was injured and decided to assist him. She used her handkerchief to cover the wound and then departed. Bronk then developed feelings for Rio. When he arrived at school, he was rubbing the handkerchief beside his face. After everyone else in the Numbers Club dismissed the idea of dating Rio, Ray suggested Bronk Duel Shark in order to get his permission. He went to Shark in order to Duel him but he refused because he claimed that Bronk wouldn't be able to beat him. He instead told him that he get at Yuma's level. After Shark walked away, Bronk was shouting Yuma's name in the air with Flip and Caswell listening in, with both misunderstanding that Yuma and Rio were together. The next day, Bronk confronted Yuma about him dating Rio. After some more confusion, the Numbers Club and Rio both end up at the tennis court to confront Shark. After Shark decided to be silent as usual, Rio insults him enough to tick off Shark and they begin to Duel. During the Duel, Bronk supported Rio even when she was at a point of losing to Shark. After the Duel the truth was revealed and confusion was still left between them. 
Along with the rest of the Super Secret Number Card Investigation Club, Bronk followed Yuma into the Barian world. He helped to ward off the monsters attacking the Different Dimension Airship with his "Tin Archduke".
After Mr. Heartland was defeated, the Seven Barian Emperors arrived together on Earth in front of Yuma. Yuma was rendered unable to Duel when the Emperor's Key reacted with Nasch's Barian Emblem. As the Emperors were about to attack, Roku and Kaze arrived, pelting the Emperors with smoke bombs. This allowed Yuma's entire group to escape. When other Duelists began to arrive to stall the Emperors, Bronk joined them, confronting Merag, who he knew as Rio. He insisted she would always be Rio to him. Merag unveiled her "Number 10X" monster, "Number 103: Ragna Zero" and later initiated a Barian's Chaos Draw alongside the other Emperors. She proceeded to use "Rank-Up-Magic The Seventh One" to Summon "Number C103: Ragna Infinity", which defeated Bronk. She acknowledged the feelings he had sent her through the Duel, but considered them little more than a nuisance. As Bronk was sent to the Barian World, he bemoaned that he couldn't return to Yuma with Rio at his side as he wished.
Tetsuo is part of Yuma's circle of friends, together with Kotori, Cathy and Takashi. At school, when Yuma keeps challenging himself with impossible tasks with his "Kattobingu" spirit, while Tetsuo usually makes fun of him, Kotori is always worried. Yuma uses to Duel Tetsuo very often; however, he apparently was never able to beat Tetsuo.
One day, Kotori and Yuma find Tetsuo has been forced to Duel by a guy nicknamed Shark, and after being defeated, he takes Tetsuo's Deck. Yuma confronts him, but Shark takes his pendant and breaks it. Enraged, Yuma challenges him to a Duel. Shark accepts it, and says that they will Duel on Sunday, in the train station.
Later, Yuma keeps searching for the other half of his broken pendant until late, and Kotori stays with him all the time. Tetsuo then appears and tells Yuma not to go, as he would never be able to win, and that it was a problem of his. But Yuma declines, saying that that's already a problem of his as well, as Shark broke his most important thing. Tetsuo then gives 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. Sunday, when Yuma goes to Duel Shark, Kotori and Tetsuo go to watch the Duel and cheer Yuma up. During the Duel, as Astral appears to Yuma, Kotori gets worried about him talking "to himself". Yuma then asks if she and Tetsuo can't see Astral, and they say they can't. Later, when Yuma defeats Shark, Kotori and Tetsuo then congrats him in joy.
After their escape from the park, Yuma and the members of the Numbers Club gather in Cathy's house. Tetsuo asks Cathy what she wanted to show them. She then presses a cat paw-like button, which opens a door leading to a big room, with many researchers and big computers. Cathy explains that as an apology for the trouble she caused, the Numbers Club's headquarters would be established there, where they can look up mysterious phenomenons happening throughout the world, and therefore, locate the "Numbers".
Yuma tells them that Astral told him that now he got three "Numbers", some of his memories have returned. Yuma asked what he remember, and Astral says his enemy is Dr. Faker, who plans on using 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 decides to save the world from Dr. Faker.
Another day, the Numbers Club is gathered at Cathy's mansion, when a big monitor detects a huge source of energy coming from a Duel involving a "Numbers". Tetsuo rushes over there, and finds a Numbers Hunter. Meanwhile, Kotori calls Yuma, who is sleeping at home, and tells him about Tetsuo. They go immediately after him, but when they arrive there, they find Tetsuo laying on the ground, injured. Tetsuo gives his Deck to Yuma in order to help him improving his Deck. Yuma uses Tetsuo's cards and do so. Right then, Tetsuo is hospitalized.
Yu-Gi-Oh! D Team ZEXAL
In the spin-off manga Yu-Gi-Oh! D Team ZEXAL, Tetsuo forms a Dueling Team with Kotori, Takashi and Yuma, called Team ZEXAL. Yuma is accompanied by a Dueling Ghost called Astral, but he can only be seen by Yuma. By that way, when Yuma talks to him, the others think he is talking to himself. This, in addition with Yuma's arriving late for the team's first meeting, makes Kotori and Takashi worry about Yuma being the leader, and Tetsuo challenges him to a Duel - if Tetsuo wins, he will be the leader. Yuma accepts the challenge, and wins, so that others accept him as the leader.
So far, only one card of Tetsuo's Deck was shown in the manga. However, Yuma mentioned to his sister in Rank 1 that he was beaten at least 40 times by Tetsuo. He later gave Yuma his Deck to help him defeat Eviluder.