Changes

After this ban, Reginald turned into a delinquent and began to steal the Decks of his opponents once he beat them. It is known by most students within [[Heartland Middle School]] that Reginald was not only a skilled Duelist, but also a bully.<ref name="ep1">{{episode|Yu-Gi-Oh! ZEXAL|1|ref}}</ref> He obtained the nickname "Shark", due to the fact that he used an ocean-themed Deck and because he ripped his opponents' Decks out of their hands swiftly and with malice. Despite Reginald's actions, [[Yuma Tsukumo]] defended him, as he believes that everyone has done something in their past which they regret.<ref name="ep12">{{episode|Yu-Gi-Oh! ZEXAL|12|ref}}</ref>

Shark defeated opponents at his school, taking their Decks after they lost. After defeating [[Bronk Stone]] , he met [[Yuma Tsukumo]], who attempted to defend Bronk. When asked what his most important thing was, Yuma told him it was his [[Emperor's Key|pendant]]. Shark ripped the pendent from his neck and threw it away. Shark challenged him to a match, with both Yuma's and Bronk's Decks on the line. Yuma accepted.<ref name="ep1">{{episode|Yu-Gi-Oh! ZEXAL|1|ref}}</ref>

Sometime after the Duel, words of Shark's defeat spread around school and his reputation dropped. Eventually, he stopped going to school and also quit Dueling, and was taken in by a gang led by [[Scorch]] and [[Chills]], who hung out at an [[Heartland Arcade|abandoned arcade]]. One night, Shark was riding on his motorcycle, and stopped after seeing Yuma, staring at him before riding off.<ref name="ep8">{{episode|Yu-Gi-Oh! ZEXAL|8|ref}}</ref> One day, while Yuma was late to school, Shark drove across a road on his motorcycle and nearly hit Yuma. After Yuma is belittled by his friends who believe that his victories over Shark and [[Flip (character)|Flip]] were just because of his "[[Number]]s", he decided to find Shark and challenge him to a rematch, without using the help of [[Astral]] or his Numbers. When Yuma found Shark, he refused to Duel as his previous loss to Yuma caused him to give up Dueling. Scorch and Chills nearly hurt Yuma and his friends, but Shark told them to stop, by saying he knows them. After the gang let Yuma go, he chanllenged Shark, he refused to Duel as his previous loss to Yuma caused him to give up Dueling. Yuma proceeded to chase Shark and annoy him by requesting a Duel until he accepted. , Yuma bet [[Emperor's Key]] on the result. Yuma did not use his "Numbers" and Shark told him to do so, believing a victory over Yuma without "Numbers" would be meaningless. Yuma Summoned "Utopia", which Shark weakened with "[[Friller Rabca]]". This let "[[Black Ray Lancer]]" [[negate]] its effects and destroy it, which impressed Astral. Shark won with a [[direct attack]] from "[[Submersible Carrier Aero Shark]]". Shark took the Emperor's Key, but threw it on the ground as he walked offafter he remember what Yuma said about being friends. Before driving away, telling Shark told Yuma that Scorch and Chills gives him a place to belong and told him Yuma not be bother him again.<ref name="ep10">{{episode|Yu-Gi-Oh! ZEXAL|10|ref}}</ref>

Shark soon overheard Scorch and Chills' plot of raiding the Heartland museum in hope of trying to steal a valuable Deck containing "[[Chaos End Ruler -Ruler of the Beginning and the End-]]". He also shocked to discovered that both thugs were possessed by "Numbers". When Chills and Scorch found Shark listening on their plan, he was forced to go along with them, even though he knew this plan was dangerous. Before going, he tells another gang member, [[Weasel]], to run so he doesn't become involved in the dangerous raid. , but Weasel went and warned Yuma of the situation instead. Upon arriving at the museum, they found Yuma standing in their way, not allowing them to pass without beating him in a Duel first. He was shocked when Yuma bet his "Number 39: Utopia" on the Duel. Shark warned Yuma not to be concerned for him, but Yuma said he won't leave him alone to rob the Deck. Yuma also pointed out that Scorch and Chills were using him, and that their hideout is not a place for him and insisted that he and Shark were comrades. Shark then decided to Duel with Yuma against Scorch and Chills in a 2-on-2 [[Tag Duel]]. On his first move, he Xyz Summoned "Submersible Carrier Aero Shark" and managed to deal [[effect damage]] to Scorch. Scorch Xyz Summoned "[[Number 61: Volcasaurus]]" and [[activate]]d its effect, which destroyed "Submersible Carrier Aero Shark" and dealt Shark damage equal to the ATK of "Aero Shark".<ref name="ep11">{{episode|Yu-Gi-Oh! ZEXAL|11|ref}}</ref>

Just when Orbital 7 was about to kill him with a drill, [[Kite Tenjo]] stepped in and called a halt. Shark and Kite both chatted a little about their connection to Yuma, and Shark refused to give Yuma's key to him. After hearing Kite mention the "[[Numbers]]" cards, Shark relized he is the "Number Hunter" and then lied to Kite about having a "[[Number]]" card, then a Duel is startedover the possession over [[Emperor's Key]]. Shark was confident about his Deck's new Anti-"Numbers" strategy , which proved effective against Yuma. However, he still wanted to have a "Number", so he planned to steal Kite's "Numbers", but Kite noticed it and used "[[Number 30: Acid Golem of Destruction]]" so that its negative effects damage Shark when he steals it. Shark remembered that Yuma would never give up, grasped the key and continued the Duel. When Shark lost, he apologized to Yuma being that he failed to protect the [[Emperor's Key]]. Shark's soul was taken by [[Photon Hand]], causing him to he age considerably and become comatose. However, Kite was surprised that the soul didn't possess a "Number" card, but still took his soul when Yuma arrived.<ref name="ep22">{{episode|Yu-Gi-Oh! ZEXAL|22|ref}}</ref>

At the beginning of the [[World Duel Carnival]], he met Yuma, who was panicking because he didn't have a [[Heart Piece]]. When he was asked if he would be participating, he Shark replied he didn't feel like it. When he drove down the road a bit further, he caught a thrown "[[Mirror Force]]" card, the card that Shark associated with his ban from the National Circuit, and it turned out to be [[Quattro]], his opponent in his last pro Duel. Quattro explained he purposely put his Deck where Shark could see it, to get him disqualified.<ref name="ep26" />

[[File:Reginald Kastle.jpg|thumb|240px|left|Shark listens to [[Fuma]] challenging Yuma.]]One day after school, Shark went to visit Rio in the hospital, but ran into Yuma on the way, who suggested they Duel. Shark apologizes and declines Yuma because told him he had to go see Rio, then he sensed the arrival of [[Gilag]]. Getting an urgent call from the hospital about Rio, Shark rushed there with Yuma and Tori to find Rio crying out in pain. The doctor told Shark that Rio's condition had worsened thirty minutes prior. Rio claimed that disaster was coming and that "they" were coming to take the most important thing, though Shark was confused who are "they". Yuma was called away to save his friends from [[Fuma]], Shark attempted to follow, but Rio clutched his hand and stopped him.<ref name="ep74">{{episode|Yu-Gi-Oh! ZEXAL|74|ref}}</ref> Later, Shark eventually left the hospital and intercepted part of Fuma's gang, while Kite intercepted another part of it. The two defeated all of them and then arrived at [[Heartland Middle School]] to inform Fuma of his gang's failure and give his support to Yuma to battle against the [[Barian World]].<ref name="ep75">{{episode|Yu-Gi-Oh! ZEXAL|75|ref}}</ref>