Allen Kaboom, known as Allen Kozuki (
Allen is a short boy with red spiky hair and bushy eyebrows. His eyes are teal and the front of his bangs are lined with yellow. Allen wears a maroon long-sleeved shirt, grey pants and yellow boots with white tongues and grey soles under a purple poncho that is emblazoned with a blue shield shape and green diamonds; two on the lower part of the shield and two smaller ones on each shoulder.
Allen is a friendly and light-hearted individual, though not to the point of ignoring suffering. He cares about the well-being of his friends, encouraging Sayaka not to overwork herself and he was saddened to learn of Yuto's disappearance. He dislikes Yusho Sakaki for (seemingly) abandoning them before the invasion of Duel Academy. This dislike extends to Yuya, calling him an outsider after learning he is Yusho's son despite their initial friendly meeting. Allen speaks somewhat informally, as noted by Sylvio.
Prior to Duel Academy's invasion, Allen and Sayaka were students from Heartland Duel School's Clover Branch, the same branch where their friend and ace Duelist Kite studied. One of their teachers was Yusho Sakaki. During the invasion, they became members of the Resistance. Eventually, most of the Clover branch-based survivors were wiped out and they were forced to go into hiding at the Duel Sanctuary.
While Yuya Sakaki and Kite were Dueling, Kite mistook Yuya for Yuto. Allen, Shay, and Sayaka arrived and cleared up the misunderstanding. They attempted to convince Kite that the Lancers were comrades and to rejoin them, but Kite refused and disappeared.
After leading the Lancers to their hideout, Allen introduced himself and Sayaka to Yuya, Gong and Sylvio. Sayaka was handing out food to civilians, and Allen advised her not to overwork herself. He then commented on Yuya's resemblance to Yuto, and he asked if Yuya was sure that he wasn't Yuto, but Shay clarified that Yuya was not Yuto. After Shay explained where he and Yuto had gone, Allen revealed that while Yuto and Shay were gone, Duel Academy had launched a massive offensive attack, wiping out the Resistance's Spade Branch and forcing the remnants of the Clover Branch to go into hiding. Their conversation was cut short when Sayaka questioned Yuya's connection with Yusho, and Yuya revealed that Yusho was his father. Allen explained that Yusho was their teacher and that he had abandoned them during the invasion, shocking Yuya.
Allen and Sayaka left the hideout in search of Kite, and found him Dueling three Duel Academy Duelists. Kite told them to stay out of his way and he sealed the Duelists into cards. Allen told Kite that Sayaka was worried about him, but Kite ignored him. Shay arrived and he challenged Kite to a Duel. During the Duel, Allen and Sayaka learned about Action Cards from Sylvio when Shay used one. Yuya showed up to stop the Duel, and Allen told him that he should stay out of their business as he was an outsider. As Shay continued to try to convince Kite to fight alongside them again, Yuya mused on their past, and Allen wondered how Yuya knew those details. Yuya revealed that Yuto was inside him. Shay lost, and Kite prepare*-d to seal him into a card, but Sayaka begged him not to, explaining that she didn't want to lose him after they had lost Lulu. Allen tried to reassure Sayaka that it wasn't her fault, but Sayaka revealed that she had been present and too scared to intervene when Lulu was kidnapped. This convinced Kite to spare Shay, and Kite departed.
Later, while Allen was working on his Rollerboots, he saw Sayaka run off and he went after her. As he searched outside, he almost ran into Yuya, who asked Allen to take him too because Sayaka was going after Kite. Allen refused, claiming that he would never accept Yuya as a comrade even if Yuto was inside Yuya. Allen found Sayaka cornered by Gloria and Grace, and he told Sayaka to run, but she refused, and Gloria and Grace suggested a Tag-Team Duel. Allen Summoned "Ruffian Railcar" and inflicted damage on his first turn, then protected "Ruffian Railcar" from "Amazoness Queen" with "Construction Train Signal Red" to set the field up for Sayaka. Sayaka's attack failed, and to Allen's anger she forgot to use the effect of "Fairy Cheer Girl". Seeing Sayaka's sorrow, Allen tried to reassure her that he would make up for it on his next turn, but Gloria and Grace mocked the idea and they revealed that they were the Tyler sisters, who Allen remembered had destroyed the Spade Branch Resistance force. Allen and Sayaka were pushed back by the Tyler sisters' "Amazoness Pet Liger", and Sayaka apologized to Allen for being a burden. Allen reassured her that they hadn't lost yet, and he Xyz Summoned "Heavy Armored Train Ironwolf" and used its effect to let it attack directly but the Tyler sisters revealed that the effect of "Liger" would negate the attack. Sayaka reminded Allen that he could use the effect of "Cheer Girl" to draw a card, and Allen drew "Limiter Removal" and immediately attacked. Grace used Amazoness Substitution to switch the attack to Gloria's "Amazoness Swords Woman", and Allen used "Limiter Removal" to double the ATK of "Iron Wolf". Grace used the effect of "Swords Woman" to reflect the damage back to him, but Sayaka saved him with "Fairy Rail", turning the damage into ATK for "Cheer Girl". Sayaka told Allen to use "Fairy Cheer Girl" for the next attack and they were able to turn the Duel around. However they were both defeated when Gloria Fusion Summoned "Amazoness Empress", which allowed the twins' "Amazoness" monsters to inflict piercing damage. Just as the Tyler sisters prepared to seal Allen and Sayaka into cards, Gong and Sylvio arrived. Their would-be rescuers were also defeated by the Tyler sisters while Allen remained unconscious. He awoke to see Yuya and Shay Dueling the Tyler sisters as the sisters gained LP from "Amazoness Hall". Allen was amazed by Yuya's Dueltaining as he used "Miracle Rocket Show" to defeat the Tyler sisters.
After the Duel, Allen finally accepted Yuya as a comrade, and he, Sayaka and the Lancers watched Shay and Yuya Duel three Obelisk Force members, with the Lancers and Sayaka. The Obelisk Force eventually Summoned "Chaos Ancient Gear Giant", and the shockwave from its attack damaged the surrounding buildings and caused Sayaka to flee in fear into the debris zone. Shay saved her, but to Allen's worry he had been badly injured by the debris in the process. Allen was surprised when Kite returned to help Yuya win against the Obelisk Force.  A squad brought by Duel Academy Commander-in-chief Aster Phoenix started to surround them, but Kite defeated them, allowing everyone to escape while Yuya Dueled Aster.
They reached their hideout, and Allen and Kite returned with their Resistance comrades to assist Yuya, arriving just as Mamoru Noro ordered the Duel Academy soldiers to attack Yuya and the defected Aster and the Tyler sisters. Allen explained that Kite had brought everyone to help him and that Shay was being looked after by the others. Kite challenged Mamoru to Duel him if he had the resolve to put his life on the line, forcing the frightened deputy to surrender. Aster made a speech convincing the Duel Academy Duelists to stand down and assist the people that they had wronged, and the students all agreed. Back at the Duel Sanctuary, Allen expressed his concern over their decision to let Aster and his former Duel Academy squad come to their hideout and help them. He was surprised when Kite admitted his mistakes after seeing Aster do the same, despite Allen reminding Kite that Duel Academy had sealed his family into cards. He listened to Yuto, who was speaking through Yuya, assure Kite that he was showing bravery by admitting his own mistakes and enduring the pain of losing his family and friends. To Allen's surprise, Aster revealed that there was a way to restore the people who had been sealed into cards, but they would have to retrieve the cards from Duel Academy. Yuya, Gong, Sylvio and Kite prepare to depart for the Fusion Dimension, and Allen gave Yuya his rollerboots and told him that they were his feelings.
A dimensional rift opened in the sky, and Allen wondered what the massive dragon that he could see in it was. Another rift opened and started to pull people inside, and Allen told Sayaka to hurry but she was distracted the sight of Shay and Kite Dueling on the other side of the rift. A rift opened in front of her, and Allen tried to save her but they were sucked into it and transported to the Fusion Dimension. They woke to find themselves present as Shay and Kite Dueled an opponent who they called Yuto and Yuya. Allen was amazed when Shay and Kite used "Rank-Up-Magic Limitover Force" to Rank-Up their monsters without knowing what the other had in their hand. Kite used "Rank-Up Gravity" to force his opponent's monsters to attack and banish them if they didn't, a strategy Allen thought perfect since Shay and Kite's monsters had the higher ATK. However, their opponent used the effect of his "Supreme King Servant Dragon Dark Rebellion" to reduce the ATK of their monsters to zero. Before Allen and Sayaka could see anymore, another rift opened, transporting them to another dimension.
Allen and Sayaka found themselves outside You Show Duel School, as the portion of Paradise City that they were in was merged with the other dimensions. They noticed an island passing with several of their Resistance comrades who had been sealed into cards, and they realized that their comrades had been freed. Allen was surprised to learn that the opponent Shay and Kite had Dueled, Zarc, was the huge monster, in addition to resembling Yuya. Declan Akaba joined the Duel and managed to deal damage to Zarc, and Allen and Sayaka told him to deliver their thoughts to Yuya. However, they were surprised when they thought "Supreme King Z-ARC" had killed Declan.
Following the battle against Zarc, Allen told Yuya that Shay was in the Fusion Dimension and didn't care about the Junior Arc League Championship after learning about it from Declan. He then watched Yuya and Dennis McField's Duel, amazed by Dennis' Rank-Up and Yuya enduring the attacks of "Performage Trapeze High Magician". He was happy when Yuya won. Allen is later seen watching Yuya's Duel against Jack Atlas with Gloria, Grace, Mamoru, Aster, Kite, and Sayaka. Allen and Sayaka were happy when Yuya brought out "Dark Rebellion Xyz Dragon". Allen applauded Yuya's victory and also watched his Duel with Declan. When Yuya's "Starving Venom Fusion Dragon" was attacked by Declan's "D/D/D Doom King Armageddon", Allen encouraged Yuya to use the Rollerboots, but to his surprise, Yuya instead flew up with "Starving Venom" to grab an Action Card. He was amazed when Yuya used the effect of "Odd-Eyes Venom Dragon" effect to increase its ATK by the combined ATK of Declan's monsters. Allen was surprised when he thought Yuya defeated Declan and noted how Yuya was smiling after he used the effect of "Performapal Five-Rainbow Magician" to lower their monsters ATK to 0. He watched Yuya and Declan gather Action Cards to in order for one of them to win the Duel first due to "Five-Rainbow Magician". Allen was happy that Yuya won and was sent to the Pendulum Dimension by Ray Akaba to witness her revival as Zuzu Boyle.
Allen uses a "Railway" Deck based around power tactics.
|Gloria Tyler and Grace Tyler||107||Lose (with Sayaka Sasayama)|
- ↑ 1.0 1.1 1.2 1.3 1.4 Yu-Gi-Oh! ARC-V episode 103: "The Brilliant Machine Angels"
- ↑ 2.0 2.1 Yu-Gi-Oh! ARC-V episode 102: "Rush for Revenge"
- ↑ 3.0 3.1 Yu-Gi-Oh! ARC-V episode 147: "The Unleashed Dragons"
- ↑ Yu-Gi-Oh! ARC-V episode 105: "Fighting For Friendship"
- ↑ Yu-Gi-Oh! ARC-V episode 107: "The Tyler Sisters"
- ↑ Yu-Gi-Oh! ARC-V episode 108: "Calm and Concentration"
- ↑ Yu-Gi-Oh! ARC-V episode 109: "A Surprise Behind Each Other"
- ↑ Yu-Gi-Oh! ARC-V episode 110: "Anger and Smile"
- ↑ Yu-Gi-Oh! ARC-V episode 112: "Toward a City Filled with Smiles"
- ↑ Yu-Gi-Oh! ARC-V episode 136: "Reign of the Supreme King Dragon"
- ↑ Yu-Gi-Oh! ARC-V episode 137: "The Rebellious Supreme King Servant Dragon"
- ↑ Yu-Gi-Oh! ARC-V episode 139: "The Eyes Tainted by Darkness"
- ↑ Yu-Gi-Oh! ARC-V episode 140: "Pendulum of the Soul"
- ↑ Yu-Gi-Oh! ARC-V episode 144: "The Cursed Gear Mask"
- ↑ Yu-Gi-Oh! ARC-V episode 146: "Dimension Highway"
- ↑ Yu-Gi-Oh! ARC-V episode 148: "The Miracle Drawn by the Pendulum"