Reginald Kastle

Ryoga Kamishiro, nicknamed "Shark", is one of the main characters in Yu-Gi-Oh! ZEXAL and is one of Yuma Tsukumo's friends and rivals. He was originally a cold and malicious person, but has grown quite humble.

Design
Ryoga has dark blue eyes, pale skin and dark purple hair, similar to tentacles hanging down, befits his Deck theme of aquatic creatures, as his hair is similar in appearance to an octopus. His other accessories include a grey, shark tooth-shaped pendant, and two grey rings on his right hand. He also owns a grey and green Duel Gazer with a red lens and a yellow spike. In the manga, he also wears a large red jeweled, yellow pendant that vaguely resembles a spaceship.

His attire includes a dark purple jacket over a black shirt and dark pants. When in his school attire, he wears a white shirt with green-lined sleeves, tie and a collar. During his National Circuit days, Ryoga wore a white top with a purple waist coat and his usual dark pants.

Personality
After being disqualified from the National championships for trying to look at the another competitor's deck, Ryoga became bitter and uncaring, the way he held himself at the beginning of the series. Cold and malicious, Ryoga flaunts his power by taking the Decks of the people he defeats, making them squirm in the process, such as when he defeated Bronk Stone. When he became possessed by the Numbers, he became quite violent, destroying the scenery surrounding him throughout the Duel.

However, he does have some honor; as he returned Bronk's deck upon losing to Yuma as he promised and keeping all the decks he'd stolen from people completely intact. His defeat to Yuma seems to have humbled him in a way - he is no longer overly cruel to people, as shown when he returns Yuma's pendant after winning an Ante Duel with it at stake. He also seems to put more faith in bonds and friendship, shown by his willingness to form a team with Yuma during the Tag Duel with Rikuo and Kaio. He further entrusts Yuma with a card that would allow them to win the Duel.

Ryoga also tries to rescue Emperor's Key from Kaito and Orbital 7 when it is stolen, clearly stating that he sees Yuma as his friend. In the Duel with Kaito, Shark remembers Yuma, and that Yuma would never give up. Before Shark's loss to Yuma, he hated people who never gave up.

Ryoga's friendship with Yuma has also helped him in handling the Numbers cards. When Ryoga first got in contact with them Number 17: Leviathan Dragon, it could easily take a hold of him. However, he was able to fight off the influence of Number 32: Marine Biting Dragon - Shark Drake because of his bond with Yuma, making him the first known person to be able to resist the influence of the Numbers without a special item or power. Despite being able to resist Number 32's influence, Tron said that it did infected him and it will amplify his darkness caused by his desire to take revenge against IV.

National Circuit Days
In the past, Ryoga was a well-known and popular Duelist within the National Duel Circuit. The pressure got to Ryoga's head, causing him to become desperate because he wanted to support his sister, who was in an accident being heavily injured. While preparing for the finals and in the waiting room, he notices that his his opponent dropped and left his deck. While not intentional, Ryoga's desperation got the better of him and ultimately looked at the visible cards on the floor. Midway through his duel, while neither duelist had a visible advantage, Ryoga was disqualified canceling the match, as he was found out to have looked at his opponent's cards. This also caused him to be permanently banned from the Duel Circuit.

After this ban, Shark 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 Highschool that Ryoga was not only a skilled duelist, but also a bully. 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 Ryoga's actions, Yuma defended Ryoga, as he believes that everyone has done something in their past which they regret. Yuma recalls how he used "Numbers" even when he promised he wouldn't, because he was afraid he would lose.

It is later revealed that IV set up by carefully placing his Deck on the edge of a pot so it would tip over. Once the Deck fell, it drew Ryoga's attention, and he was prompted to look at the cards. IV also revealed that Ryoga won't be able to fulfill his promise to his sister.

Present Day
Shark first appeared whilst Yuma Tsukumo and Tori Meadows were observing the Duels going on within their middle school grounds. He was seen quickly defeating Bronk Stone without taking one point of damage, after this he then took Bronk's Deck and belittled him along with his friends. When Yuma stood up for Bronk, Shark asked Yuma what was most precious to him, to which Yuma looked down at his pendant. Seeing this as a chance, Shark snapped Yuma's pendant and broke it whilst his friends restrained Yuma from hitting Shark. Shark then suggested that Yuma should Duel him in order to retrieve Bronk's Deck back, to which Yuma accepts.

Shark is then seen within the city square, and then begins his Duel with Yuma. Within the Duel, Shark quickly gains an advantage with his "Big Jaws" and "Aqua Jet" combo. He then corner Yuma with his traps, and then his passion for winning Duels gets the better of him and allows him to be possessed by Numbers to which he then proceeds to Xyz Summon "Number 17: Leviathan Dragon".

As the Duel progresses, Shark begins to toy with Yuma, taking his Life Points down to a small fraction. However, Yuma managed to come out of this with the hlep of Astral, and managed to defeat Shark with his "Number 39: Utopia" at 5000 ATK, which knocks Shark out, winning Yuma the match. When Shark awoken, and he gave Yuma back Bronk's Deck, as promise. Shark said that Yuma is different than everyone that he has faced before and walks off silently.

Sometime after the duel, words of Shark's defeated spread around school and his reputation to dropped. He also began stop dueling and going to school all together, and hanging out an gang run by two brother, Rikuo and Kaio. He is then later seen riding on a rouge single, thick wheel motorcycle, after Yuma's Duel with Nelson Andrews, staring at him before riding off.

One day, whilst Yuma was late to school, Shark ran across a crossing and nearly hit Yuma whilst he was on his motorcycle. After Yuma is belittled by his friends who believe that his victories over Shark and Flip were just because of his Numbers, he decides to find Shark and challenge him to a rematch, without using the help of Astral or his Numbers.

When Yuma finds Shark, he refuses to Duel as his previous loss to Yuma caused him to give up Dueling. Yuma then proceeds to chase Shark and annoy him by requesting a Duel until he accepts (based on his reactions during the duel it can be assumed that he only accepted in order to defeat the Numbers.). As the Duel progresses, Shark's burn strategy begins to take its toll on Yuma. Shark tells him use his "Numbers" anyway, so Yuma brings out "Utopia". It was not enough, as Shark weakened it with "Friller Rabca", then proceeded to negate its effects and destroy it with his "Black Ray Lancer". With a final direct attack from "Submersible Carrier Aero Shark", Yuma lost the Duel, losing his pride along the way. Yuma bet his pendant in the Duel as a prize, but when Shark took it, he threw it behind him onto the ground beside Yuma, saying that it wasn't worth destroying as well as warning him not to bother him again.



Shark soon overheard Rikuo and Kaio's plot of raiding the Heartland museum in hope of trying to steal a valuable deck. He also discovered that both thugs were possessing two Number cards. When Kaio and Rikuo found Shark listening on their plan, he is forced to go along with them. Before going, he tells their younger brother, Ginji, to run so he doesn't become involved in the dangerous raid.

Upon arriving at the museum, he found Yuma standing in their way, not allowing them to pass without beating him in an 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 Rikuo and Kaio were using him, and that their hideout is not a place for him to stay plus both Yuma and Shark are comrades. Shark then decides to duel with Yuma against Rikuo and Kaio in a 2-on-2 Tag Duel. On his first move, he Xyz Summoned "Sumbersible Carrier Aero Shark" and managed to deal effect damage to Rikuo. But after Rikuo Xyz Summoned "Number 61: Volcasaurus," he activated "Volcasaurus's" effect, which destroyed "Submersible Carrier Aero Shark" and dealt Shark damage equal to "Submersible Carrier Aero Shark's" ATK.

Having all their moves countered and with the appearance of "Number 19: Freezerdon", which gave "Volcasaurus" its Overlay Units back, Shark and Yuma were pushed into a corner. After summoning "Utopia" and having it prevented from attacking by Kaio's trap "Avalanche", Yuma used its effect to protect Shark from attacks which would have caused him to lose. After having "Utopia" and the newly summoned "Black Ray Lancer" are destroyed by "Volcasaurus" (avoiding losing by "Damage Diet"), Shark narrowly avoids losing from a direct attack by using the trap "Last Entrust", ending the battle phase and giving Yuma a card needed to win. After eliminating Kaio by forcing him to use his "Compensation Exchange" trap, which saved Volcasaurus by taking damage equal to its ATK, Yuma used "Monster Reborn" to bring back Shark's "Black Ray Lancer" and equip it with Shark's "Armored Xyz" he entrusted to him earlier. It allowed him to give "Lancer" the properties of "Utopia", letting it destroy "Volcasaurus" and attack directly for the win. Afterwards, Shark comments that his card was able to improve Yuma's game, allowing him to keep it before smiling and walking off.

When Tori was trying to ask people about the Number cards, she ran into Shark, who told her that she should not get involved with those cards and that they are things that neither of them should understand in detail.

When Orbital 7 attempted to steal the Emperor's Key, he retrieved it and was chased around the school by Orbital 7. Just when Orbital 7 was about to pierce him with a drill, Kaito Tenjo stepped in and called a halt. Shark and Kaito both chatted a little then the duel started. Before the duel started he was confident about his deck's new Anti-Numbers strategy which proved to be effective before, but he still wanted to have a "Number", so he planned to steal Kaito's "Numbers", but Kaito noticed it and used Number 30: Acid Golem of Destruction so that its negative effects damage Shark when he steals it. He remembered that Yuma Tsukumo 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. His soul was taken in by the Photon Hand and he became an elderly. However Kaito was surprised that the soul didn't possess a Number card. He absorbed the soul when Yuma and his friends stepped in.

Shark was then maintained in the hospital, being look after by Mr. Kay. After Astral and Yuma drew with Kaito, he decided to release Shark's soul as he wasn't a Number controller to which returned to Ryoga where he awoke in hospital to be greeted by Mr. Kay who told him that it was Yuma who took him to the hospital. Shark then looks out of the window to support Yuma in his fight against Kaito.

World Duel Carnival
At the beginning of the WDC, he met Yuma who was panicking because he didn't have a Heart Piece. When he was asked if he would be participating, he 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 associates with his ban from the National Circuit, and it turned out to be IV, his opponent in his last pro duel.



IV explains he purposely put his Deck where Shark could see it, to get him disqualified. IV also reveals that at that time Shark was not only affected by the pressure of the Finals, but also because of a promise he made to his sister who had an accident and was hospitalized, so he was easily tempted to look at IV's deck, IV also says that maybe his sister's accident was not really a coincidence. Infuriated, Shark demands to duel with him again, but IV tells him to wait for the WDC and tosses him a Heart Piece, and leaves. Shark then decides to participate after all, to get his rematch with IV. He fell into IV's trap again as Tron told him to force Shark to participate in the carnival, probably because they want him to help them collect the "Numbers".

After Kari Tsukumo ordered Yuma to find Charlie McCoy, he overheard a crowd cheering. Knowing that it would be a duel, Yuma ran over to see Shark defeat an unknown duelist via Submersible Carrier Aero Shark's Air Torpedo effect. After the duel, Yuma congratulated Shark and asked him why he had decided to enter the WDC. Ryoga told Yuma about how IV had mistreated his sister into the hospital to trick him into being kicked out of the nationals, and now he wants a rematch with IV, but after that, he will quit the WDC. Shark tells Yuma not to get involved with him and then wandered off, vanishing from sight of Yuma and Tori.

During the second day of the WDC, after IV defeats Bronk and Caswell in a Battle Royale Duel, Ryoga charges into the area on his motorbike, asking him if he remembers the face of his "Number one fan". IV appears amused, and leaves in a cloud of dust. III puts a Duel Anchor onto Shark, preventing him from chasing after IV. In the proceeding duel, Shark takes control of III's Number monster, "Number 32: Marine Biting Dragon - Shark Drake". The Number pierces his claws into Shark's chest, but Shark's strong will overcomes the power of the Number and he uses it's power to defeat III. Although he was able to withstand the "Numbers" by remembering his time with Yuma, Shark still wants his revenge against IV for his sister, which allows "Shark Drake" to infect Shark with a small virus that will amplify that darkness even further. According to Tron, this will help them with their plan to recruit Ryoga to their side.

When Yuma, Tori, and Astral were looking for Haruto Tenjo, Shark saw them from the road above them and stopped. He overheard Yuma calling out for Kaito with his D-Gazer, interested by hearing Yuma say the name of the one who had brutally defeated him some time before and took his soul.

Decks
Ryoga's Deck is a WATER Deck consisting of monstrous looking sea creatures such as various races of sharks. He utilizes a Burn strategy in order to quickly gain the advantage through cards such as "Submersible Carrier Aero Shark" and "Explosive Urchin", with a focus on using Level 3 monsters to Xyz Summon Rank 3 Xyz Monsters for Beatdown purpose.

Trivia

 * Ryoga resembles Joey Wheeler as they're both bullies of both protagonists Yuma and Yugi in the beginning of the series, but then they become good friends. They both had to win their tournaments to help their little sisters in the hospitals.
 * Interesting enough, Shark is the only one to have been possessed by more than one Number monster than any other character, first by "Number 17: Leviathan Dragon" then by "Number 30: Acid Golem of Destruction" and finally by "Number 32: Marine Biting Dragon - Shark Drake". All of them are of the WATER Attribute.