He was voiced by Michael Smith.
IV has a scar on the right side of this face, and like his brothers, III and V, IV have a crest on his body; IV's crest is purple and on his right hand. He has a Duel Gazer-like pattern that appears around his eye similar to Kite Tenjo, although he has worn a regular Duel Gazer in the past.
He has large, spiky dark red and yellow hair and wears a long flowing coat with white pants, boots and a shirt which all feature a curly, high-class pattern. IV's D-Pad has the appearance of a red blade which separates into three sections. He highly resembles Takuto Tsunashi from the anime Star Driver.
IV is a sadistic and malevolent Duelist who wants to make his opponents suffer, with what he calls his "fan service", in order to win. When in the presence of his fans, his personality becomes a facade as he hides his true nature and becomes a "noble" and "well-mannered" person. He sees his fans as bad Duelists and challenges them as his "fan service". When he Duels, he initially praises their skills and lets them think they have the upper hand. When his opponents fall into his trap he shows his real self and defeats them cruelly, going so as far as to keep attacking his opponents even if they have no Life Points and claiming his "fan service" must continue. He even went so far as to show a child getting tortured on a television screen to the others for his pleasure.
During his Tag-Team Duel, it is shown that IV desperately seeks to make his opponents suffer by any means possible, and feels otherwise frustrated and angered when his "fan service" is ruined. He justifies this sadistic behavior because of what the Tron Family has suffered.
IV argues a lot with his brothers, showcasing that he is willing to let his personality get in the way of their true goal and doesn't always follow Tron's orders, unlike III and V. He also seems to have a slight fear of V, shown when he got intimidated after V got mad at him for talking back to Tron. Despite this, after III was brutally defeated by Kite Tenjo in their Tag-Team Duel , IV showed concern for his defeated brother, proving that he does care for his siblings. He showed a more caring side when III was unconscious by defending III when Tron said he was disappointed with him and III.
As a child, IV wasn't as brutal as he is now, but he had a tendency to tease III like normal brothers do and kept taking his cards. He also had respect for V back then as he returned III's cards when V told him to.
It is shown later on that his cruel behavior is far from his true self, as he later apologized to Shark, for hurting his sister, claiming he had no intentions of doing so, by playing a card Tron gave him. That card not only hurt her, but also gave him his signature scar on his face while trying to save her, and even asked Shark to save his father. He described some of his actions as "inhuman", saying he had done it all for his father's sake. Like his brothers, he only followed Tron's orders and wanted to defeat Dr. Faker with hopes that doing so returns Tron to his normal self, Byron Arclight.
When pretending to be kind, he also refers to himself using the pronoun "boku", but switches his pronoun to his usual "ore" after showing his true self.
After his father had reformed, IV still maintains his boastful attitude and his old habit of saying "fanservice", but had become more friendly. Still remorseful about his actions towards Rio, he developed an empathy for her, as he can't help but feel sorry for her suffering at Kurage's poison. IV also displayed a childish side, complaining about Kurage's "Number 4: Stealth Kragen the Deadly Poisonous Jellyfish" simply because of the "4" in its' name, which IV proclaimed the number was his "trademark". He also expressed gratitude for what Yuma and Shark had done for his family.
IV's name is the Roman numeral for four. The number of "Number 15: Gimmick Puppet Giant Killer" is a pun on IV's own name, since "I" alone is the roman numeral "one" and "V" is the numeral "five", forming "15". IV's second Number , "Number 40: Gimmick Puppet Heaven's String" is based on the true meaning of IV's name, instead of breaking it down.
In the dub, his name is in Italian, Quattro, which means Four.
IV's crest grants him various powers. It protects him from having "Numbers" extracted from him, rendering Photon Hand useless. He can produce portals to quickly travel and escape.
His crest comes with a price - it is directly connected to his soul, and should he lose a Duel while wielding a powerful "Number", he will fall comatose. He and his brother, III later acquired a bracelet that was invented by their brother, V, granting them the abilities of their father's crest once again.
He is capable of collecting "Numbers", using a process similar to Astral's. Like his brothers, IV also uses the bracelet invented by V, though the stone on his bracelet is purple.
In his younger days, IV along with his brothers and their father, Byron, lived a happy life with their dog, where he was innocent. One winter night, their father gave III a Duel Monsters card - "OOPArts Aztec Mask Golem", which III showed to IV. IV was jealous because only III received a card and tried to take "Mask Golem" from III. Chris told them to stop or their father would scold them and then promised to teach both of them how to Duel.
His father became involved in Dr. Faker's experiments, but Faker eventually betrayed both him and Kazuma Tsukumo, sending them to another dimension as sacrifices to open the door to alternate dimensions. As Byron didn't return from the trip, III and IV were were sent to an orphanage, while Chris remained at Dr. Faker's facility in an attempt to learn of their father's fate. However, after learning Kite and Hart Tenjo were Faker's sons, Chris left Heartland with his brothers. Their father returned years later, but his form warped into that of a child. He took the name "Tron" and began plotting revenge, with IV and his brothers aiding him.
As part of Tron's plan, IV was told to Duel Rio Kastle. He played a card called "Flaming Hell Blessing", which somehow set the building on fire. IV carried Reginald's sister to safety, with his face being scarred in the process, but she was critically injured in the blaze.
IV participated in the National Duel Circuit, where he faced Reginald Kastle in the finals. He set Reginald up to be disqualified by planting his Deck on top of a pot, so that it would fall and end up scattered on the floor in the break room. That way, IV ensured Reginald would see it, though Reginald himself was unaware of that until IV himself told him later.
World Duel Carnival Preliminaries
IV reappeared to Reginald and lured him to a building in construction by throwing a "Mirror Force" card at him. Shark asked why he did that, and IV responded that it was just a form of greeting before the World Duel Carnival. Shark responded that he won't participate in the tournament, and IV asked if Shark is still influenced by what happened at the Duel Circuit. He revealed that he knows about Shark's sister, who got into an accident. He told Reginald that he intentionally got him disqualified, and even implied that he caused the accident that injured Shark's sister. Shark was enraged by this, and IV taunted him, saying that on that day, he became the Duel Champion of the Far East. IV threw a Heart Piece to Shark, telling him to try to defeat him in the World Duel Carnival.
After that IV approached Tron, who was watching cartoons. He told him that he did as he was ordered - Shark will participate in the WDC. IV asked why Tron wanted Shark to enter the World Duel Carnival as he already has given up on being a Duelist. Tron responded that he is needed for when all the "Numbers" cards are collected. IV stated that he doesn't care as long as he can drag Shark into hell again. IV functioned as the Number Hunter for the Tron Family, collecting "Numbers" by luring and defeating his own fans, who he considered to be terrible Duelists. During the morning of the second day of the World Duel Carnival, IV continued to do this by studying the opponents which are available within the WDC via sheets, which contain information on them and their signature cards. Here, he throws cards at them in order to choose an opponent. Seeing this, V commented that he is too brash and suggested he treat the "Numbers" he's collected better. Angered by V challenging his ethics, he suggested V try collecting "Numbers" himself and challenged him but is quickly shot down by V being reinforced by III and Tron. After insulting Tron, V rises to his feet and tells him he won't tolerate that, IV then quickly backs off.
Later on in the day, IV agreed to meet Bronk Stone and Caswell in order to sign their Duel Disks, but had an ulterior motive to entice them to a hidden location so he can Duel them with his "Numbers" and reveal his real personality without allowing the public to see him as his true self. He suggested a Battle Royal, which they agreed to. During the Duel, he allowed them to get the upper-hand by Summoning their aces, "Vaccingale" and "Tinplate Archduke". This was all a ploy as he lured them into Xyz Summoning so he could perform two One Turn Kills with his "Number 15: Gimmick Puppet Giant Killer" and "Gimmick Puppet - Baby Face". His personality changed at this moment from the friendly and noble champion of the East, to a merciless and evil person who enjoyed the pain of others, laughing when his monster hurt Bronk and Caswell. After the Duel,Shark arrived on his motorbike, making IV smirk.
IV intended to Duel Shark then and there, but was stopped when III snared Reginald with a Duel Anchor, telling IV that Tron's orders are absolute - III is to Duel Shark first. IV revealed that he already had a full Heart Piece, and told Reginald he'll be waiting in the finals and then departed. After V brings Hart Tenjo to an abandoned gallery, IV watches as Tron begins his ritual in order to transfer all of Hart's powers and memories to himself. As the ritual continued, Hart began to feel more and more pain, which amused IV as he watched intently. After Yuma Tsukumo and Kite Tenjo break into the gallery, V sends IV and III to stop them from reaching the ritual in order for it to complete. They then appear before the pair, attaching their Duel Anchors to them, initiating a Tag-Team Duel. As the Duel began, IV instantly targeted Kite as he sees him as the bigger threat. When Yuma Summoned "Number 39: Utopia", IV and III instantly know that they have to win this Duel rather than merely stall for Tron's ritual to finish. After Yuma Summoned "Utopia", IV began to target him, destroying "Utopia" straight after it was Summoned via "Number 15: Gimmick Puppet Giant Killer". After seeing that Yuma and Kite were beginning to work together, IV decided to anger Kite to break those bonds by showing him a video of Hart being tortured through Tron's ritual. Angered by this, Kite continued to damage Yuma through "Photon Pressure World" in an attempt to rush the Duel and beat them as soon as possible. This, however was quickly stopped as IV and III had a strategy to stop Kite's "Galaxy-Eyes Photon Dragon" through "Stonehenge Shield", allowing III's "Number 33: OOPArts Super Weapon - Machu Mach", to inflict 3000 damage to Kite. As the Duel continued, Yuma constantly kept intercepting IV's and III's attempts at defeating Kite, causing IV to get extremely angry with Yuma. Yuma managed to Summon his "Number C39: Utopia Ray" and defeated IV's ace, but IV struck back by Xyz Summoning his other "Number" card, "Number 40: Gimmick Puppet Heaven's String". Despite this, Kite managed to Summon "Neo Galaxy-Eyes Photon Dragon" and defeat the brothers in one attack. After the Duel ended, Kite tries to steal IV's soul and "Numbers" using Photon Hand, but was unable to as IV's crest protected him. He vowed to get revenge on Kite and Yuma and departed with III and Tron.
World Duel Carnival Finals
After Yuma and Astral defeated III, resulting in him falling unconscious, IV implored that Tron give him new powers so he could defeat Yuma. Tron responded that he's disappointed in both III and IV. IV angrily replied that III fought against the Original Number for Tron and ended up bedridden. Tron responded that what he wants are results and if III and IV can't give them to him, he has other options - like Shark. He told IV that their role was to lure him out, which angered IV, who proceeded to confront Shark at the World Duel Carnival Finals party, who told him he would gamble everything he has to defeat IV.
The next day, the Duel Coaster began, IV witnessed Shark defeating an opponent with his "Jawsman" and complemented him, saying he's Dueling magnificently. Shark vowed not to let IV get away, to his amusement, and defeated his own opponent with "Gimmick Puppet - Bomb Egg". IV sped off afterwards, with Shark chasing him. The chase continued into the underground section of the Duel Coaster, with IV and Shark both defeating opponents while taunting one another. IV attempted to lure Shark to the Magma Field, which would part Shark at a disadvantage. However, Shark was prepared to counter the field, "Magma Ocean" by using cards such as "Plate Salvage" and "Adapting to Adversity". Shark brough tout "Submersible Carrier Aero Shark" on his first turn, inflicting 1200 damage to IV before the latter even got a turn. IV countered with "Number 15: Gimmick Puppet Giant Killer", which Shark countered with "Number 32: Shark Drake". IV was shocked to see this card, not being aware that III gave the card to Shark. He knew that Tron and V were planning something, but he didn't know what. Tron appears before him, saying that he told IV nothing about this, since he may have leaked the plan if he knew. He insisted that everyone had their own role in this - III had his, V had his and IV is fulfilling his now. IV asked what his role is; Tron told him that it is to make Shark fall to the darkness of his heart, and told him he's doing quite well so far. Tron later revealed that he wanted to use Shark as an assassin who would defeat Dr. Faker. IV is hurt, saying that he, III and V did everything for Tron, and asked why Shark was chosen as the assassin and not them. Tron responded that they all have their role, and Shark fits the role of assassin better than IV. IV set out to prove Tron wrong and continued the Duel. He then managed to Summon "Number 40: Gimmick Puppet Heaven's String" and due to "Destiny Strings", he attacked Shark a total of eight times. Tron chided IV for being reckless, saying he was always like that and suggested he try to be calm instead, as he can't be trusted. IV remembered when his father used to be kind, but after returning, he was only a demon of revenge. However, IV said he and his brothers still obediently followed his orders despite this. Shark responded that he didn't care if Tron used IV - IV was still responsible. IV believed that if he defeated Dr. Faker, his father would surely return to normal. IV told Tron he did inhuman things for his sake and yet Tron cannot trust him. Tron responded he can only trust himself and the Barian World, but IV insisted he is not a pawn like his brothers were - he is the Asian Duel Champion. Tron then supported Shark during the Duel, insisting that he had a way out as he could think calmly. This hurt IV, but Tron said he had already fulfilled his role. IV attempted a comeback with "Number 88: Gimmick Puppet - Destiny Leo", which would allow him to declare an Automatic Win on his next turn. Shark finally accepted "Shark Drake" and was able to perform a Chaos Xyz Evolution to create "Number C32: Shark Drake Vice" and defeat IV. He apologized to Shark after the Duel, but told him not to blame Tron for it and implored Shark to defeat his father and save him. IV then disappeared through a portal, adding that Shark should tell his father that his sons will wait for him. Later, IV fell unconscious afterwards, but unlike his brothers, he didn't lose his "Numbers", and shown sleeping alongside his brothers.
Yu-Gi-Oh! ZEXAL II
Quattro and his brothers later returned to Heartland via submarine where they decided it was time to make their move in the ongoing war between the Astral World and the Barian World.
After Kurage poisoned Rio and disappeared in search of Shark, Yuma, Tori and III planed to go in search of him, IV met up with them in the hospital. III asked IV to deal with Kurage, while Yuma returned "Number 15: Gimmick Puppet Giant Grinder" and "Number 40: Gimmick Puppet of Strings" to him. Later, IV appeared on the roof just as Kurage poisoned Shark, teasingly calling himself Shark's "Number one fan", and challenged Kurage to a Duel. He partnered up with Shark, stating that he was fighting not only as a favor to his brother but for Rio's sake as well. After Kurage reduced Shark to 400 Life Points with "Number 4: Stealth Kragen the Deadly Poisonous Jellyfish", IV took the third turn to Xyz Summon "Giant Grinder" and used it destroy "Stealth Kraken". As the poison continued to worsen Shark's condition, IV Summons "Gimmick Puppet of Strings" to deal massive damage to Kurage, but had its abilities blocked by Kurage's "Jelly Bind". Working together with Shark, the two were able defeat Kurage and IV received the "Stealth Kraken" card. One night, IV called III to checked on Yuma and asked if he would be alright after losing Astral, but III reassured him that Yuma would be fine.