Reginald Kastle, known as Ryoga Kamishiro (神かみ代しろ 凌りょう牙が Kamishiro Ryōga) in the manga and Japanese version and nicknamed "Shark" (シャーク Shāku) in all versions, is one of the main characters in Yu-Gi-Oh! ZEXAL. He is one of Yuma Tsukumo's close friends and rivals. Originally an arrogant and callous person, Shark was one of the first Duelists to acquire and be possessed by a "Number" and was humbled upon his loss to Yuma. Shark is later revealed to be the reincarnation of Nash (ナッシュ Nasshu), the leader of the Seven Barian Emperors. Determined to not let tragedies befall his people again, he betrayed Yuma and his friends to safeguard the Barian World. He is the only Barian Emperor not to be absorbed by Don Thousand, as well as the only Barian whose original memories were not altered. He later vanished after losing to Yuma in a Duel that had the Human, Astral and Barian Worlds at stake. He, along with the Seven Barian Emperors, were revived by the Numeron Code. Shark has dark blue eyes, pale skin and dark purple hair, which resembles tentacles hanging down, referencing his Deck theme of aquatic creatures. These "tentacles" slightly resemble pigtails, but curl up on the end. He also has a light blue "crown" in front of his forehead. His accessories include a grey, shark tooth-shaped locket, which contains a family photo of his parents, as well as himself and his sister Rio Kastle as children. He also has a scar on his right shoulder.[12] He also wears two grey rings on his right hand, but he later gives one to Rio.[13] He also owns a grey and green Duel Gazer with a red lens and a yellow spike as well as a blue D-Pad. Upon regaining his Barian identity as Nash, he threw away the locket and replaced it with his own Barian Emblem pendant, though he regained the locket after his revival. His attire includes a dark purple jacket over a maroon shirt and dark blue pants with white, green-gems shoes. When in his school attire, he wears a white shirt with green-lined sleeves, tie and a collar. During his National Duel Circuit days, Reginald wore a white top with a purple waist coat and his usual dark pants. As a Barian, he has a magenta skin tone and red and blue heterochromatic eyes with aqua markings on his face. He wears a crimson cape and copper-colored guards on the wrists, shoulders, and his legs are tipped with red stones and also wears a 'H'-shaped belt. The Barian Emblem pendant becomes larger and is engraved onto his chest. His tentacle-like hair gains more volume and he also wears a copper-colored crown piece with a red jewel on his forehead. During his past life, Nash wore golden armor over a mesh shirt, gauze on his left arm, a light brown shirt, silver pants, a blue cape, and the original Barian Emblem on his chest in the form of a pendant. Shark can be classified as a typical loner, being indifferent and cool about most things, usually sporting a stoic face or scowl. He prefers to be alone and doesn't follow a crowd, as his encounters with Yuma and others are often brief before he walks off. He also has displayed little interest in school, having had stopped going to Heartland Academy after his loss to Yuma.[14] He still skipped class regardless when he decided to come back and would idly spend his time on the school's roof, but is said to be good at studying.[15] Despite Shark's aloof and cold nature, many students at school respect his Dueling skills and he's secretly popular with female students,[16] however Rio mentions that he is still disliked and feared by other students.[17] Shark is shown to have a soft side, but has only shown it to two people - his sister and Yuma. Regardless of this, he can be insensitive and callous to both, causing fighting and arguing between them, especially when Rio brings up his strange fear of onions. After being disqualified from the National Duel Circuit, Shark became bitter and uncaring, the way he held himself at the beginning of the series. Cold and malicious, Shark 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.[1] When he becomes possessed by the "Numbers", he becomes quite violent, destroying the scenery surrounding him throughout his first Duel against Yuma, and also defeating several Duelists brutally when he was briefly possessed by "Number 32: Shark Drake.[18][19] 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.[18] His first defeat to Yuma has humbled him in a way that 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.[14] 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 Scorch and Chills. He further entrusts Yuma with a card that would allow them to win the Duel.[20] Shark also tries to rescue Emperor's Key from Kite Tenjo and Orbital 7 when it is stolen, clearly stating that he sees Yuma as his friend. In the Duel with Kite, Shark remembers Yuma, and that Yuma would never give up.[21] Shark's friendship with Yuma also helped him in handling the "Numbers" cards. When "Number 17: Leviathan Dragon" came in contact with him, it easily took hold of him.[1] However, he was able to fight off the influence of "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 initially resist the influence, Vetrix said that it did infect him and it will amplify his darkness caused by his desire to take revenge against Quattro.[22] However, after a Duel with Yuma, and seeing his bumbling antics, the darkness had disappeared.[19] owever, after accepting his fate as a Barian, he adopted his cold personality again, saying that fate drew him and Yuma together to fight against one another. Unable to consider peace as an option despite his friendships with Astral and Yuma, he attacked Earth with the other Barian Emperors. He is shown to act ruthless when Dueling, as shown during his Duel with Quattro. Throwing himself fully into his Barian persona, he incited his opponent's anger, wanting to be hated and aiming to make both himself and Quattro forget about his time as "Reginald".[6] However, it was shown he was doing this to protect the people of the Barian World. Also when Girag appeared to be in danger, Nash immediately attempted to rescue him, showing he cares for many, if not all of the Barian Emperors (with the obvious exception of Vector).[23] He even burst into tears at witnessing Dumon's death.[24] He also expresses sadness at Mizar's death.[25] In his final duel against Yuma and Astral, Nash was shown to be grief-stricken for having failed to protect the Barian Emperors and having failed to make their dream come true. He reaffirms his vow to save the Barian World with their spirits at his side and became increasingly more desperate to defeat Yuma and Astral as they continued to survive his every assault, culminating in him adopting a crazed expression in their final exchange. He was also visibly distraught when they finally managed to destroy "CXyz Barian Hope". Nonetheless, he returned back to his friendly self after losing to Yuma and being revived by the Numeron Code. During his Duel against Quattro in the World Duel Carnival, Shark merges his soul with his "Number", gaining the ability to perform Chaos Xyz Evolution with "Number 32: Shark Drake", acquiring a purple aura while doing so.[26][27] After the Duel against Vector, Shark gained the ability to see Astral.[28] He is also able to resist the "Numbers" influence after repeated exposure, no longer feeling the effects even from a "Chaos Number". Shark has also demonstrated a few unique abilities: like his sister, he could generate a red aura around his body. The power of this aura fixed Dumon's Baria Crystal and allowed him to regain his Barian form.[30] After recovering his Barian identity and powers, Nash no longer uses his mechanical Duel Gazer when he Duels; instead, his left eye acts as one. He can travel and teleport between dimensions almost instantly. He can also generate viewing screens connected to various places. Like all other Barians, he has the ability to perform a Barian Battlemorph.[31] He can also perform a Chaos Draw, a power which he also granted to the other Barian Emperors. Unlike the other Emperors, he is shown to be able to perform more than one Barian's Chaos Draw in a single Duel.[6][32][33] As the leader of the Barians he is extremely powerful, being able to even break free from the area Don Thousand bound him in after he got sufficiently enraged.[34] He is also able to fire electric bolts, as seen when he attempted to hit Vector with it. Shark plays a Xyz WATER Deck[4] 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 "Booming Urchin", with a focus on using Level 3 monsters, such as "Big Jaws" to Xyz Summon Rank 3 Xyz Monsters. Shark uses cards that can counter "Numbers", whether that be negating their effects with "Black Ray Lancer" or taking control of them with "Splash Capture". As his Xyz Monsters are Rank 3, their ATK tends to be on the lower side. He includes cards to decrease the ATK of his opponent's monsters such as "Needle Sunfish" and "Friller Rabca" to make up for this. A cautious Duelist, he includes many cards to counter Spells and Traps, such as "Sea King's Verdict", "Mystical Space Typhoon", "Plate Salvage" and "Skull Kraken". After acquiring "Number C32: Shark Drake Veiss", Shark's Deck shifted to include more Level 4 monsters in order to Summon "Number 32: Shark Drake" and became more focused on the "Shark" archetype. Similarly, after acquiring "Number 94: Crystalzero" and "Number 73: Abyss Splash", his Deck shifted to include more Level 5 monsters. Even after learning he was Nash, Shark still uses the same Deck he used before, with the addition of his own "Over-Hundred Number", "Number 101: Silent Honor ARK" and its upgraded form. He has access to multiple "Rank-Up-Magic" cards as well and still includes Level 5 monsters in order to use "Abyss Splash". In his final Duel, he utilizes the "Chaos Over-Hundred Number" cards and numerous "Chaos" support cards to call forth "CXyz Barian Hope". {the original Reginald died as a child from a car crash along with her sister, mother, and father. gets ressurected later as Nash and her sister as Marin after crash}} The current Reginald is really Nash and the real Reginald died a long time ago as Nash gained both Reginald's memories, body, and personality.