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". His sister Rio Kastle, known as Rio Kamishiro (神代かみしろ璃緒りお, Kamishiro Rio) in the Japanese version, is one of the main characters, appearing in the Yu-Gi-Oh! ZEXAL anime as well. She is the younger twin sister of Shark.[9] Rio is later revealed to be the reincarnation of Marin, known as Merag (メラグ, Meragu) in the Japanese version, a member of the Seven Barian Emperors, who became determined to follow her brother no matter what happened to them and sided with the Barian World. She was absorbed by Vector after losing a Duel to him. She was later revived after Yuma and Astral's Duel. Rio has dark pink eyes and like her brother, she has pale skin and long, thick, spiky dark blue hair with light blue bangs. Rio also wears a ring on her right little finger, which was previously owned by her brother. Rio's appearance attracts many initial admirers, including Bronk. Her attire includes a white jacket over a light pink shirt, black stockings, white skirt and shoes (her skirt is also longer, covering the bare skin showing on her legs in the dub). The left coattail of her jacket has a conch-like ornament hanging down. At school, she wears the standard uniform, with hers being green due to her status as a second year student (in the dub, her skirt is lengthened). She wears longer stockings than most female students. As the Barian Marin, her skin is chalk-white and her hair is longer with more volume and is purely dark blue instead of dual-coloured. She wears a white dress with blue and gold pieces, with large white shoulder pauldrons and gloves, with a blue midriff and a miniaturized version of Nash's Barian Emblem on her chest. She still has her pink eyes. She also has red marks on each side of her cheeks, a jeweled diadem with a gold net over the back of her hair that is adorned with green and red jewels that also has a green teardrop jewel hanging over her face. Marin's outfit in her past life was that of a priestess. She wore a long hood on her head, white heeled sandals, a white dress and three gold rings on her legs. She also wore this outfit in her current life when she was possessed by Abyss. Despite her appearance and previously spending a large amount of time in hospital, she is a confident and adamant person, getting annoyed when things do not go her way. This is usually shown when conversing with her brother. Her confident personality assists in her interests which allows her to conquer sports such as soccer, baseball, basketball and boxing with ease. Despite all of this, Rio also shows somewhat of a childish side as well, shown by her fear of cats (this showing she has ailurophobia) and calling Shark a "meanie" when he teasingly refused to help remove one from her sight. Rio tends to be annoyed when people refer to her as "Shark's sister" instead of calling her by name as indicated by Yuma due to her snapping at him when he continually calls her as such, and especially does not like it when someone insults her brother. This is further seen many times during her Duel against Lotus as she got mad at her for making a rude remark about Shark. Despite being occasionally irritated with Yuma for not addressing her properly as "Rio", his personality and playful antics makes her let it slide given that she is thankful to him for helping her brother and being his friend. It is also revealed that she goes very far on things and acts strong because she feels she has to or people may use her as a shield against her brother.[2] She later shows admiration towards Yuma and Alito as she commented they have amazing Dueling spirit.[11] She takes great pride in her abilities and effort as she has no problem in showing them when people underestimate her as she believes women are not to be viewed as "pretty decorations".[2] Rio also has a empathetic quality to her personality as well. This is demonstrated when she finds Bronk injured on the way to school, and shows genuine concern to him and helps treat his injuries.[12] She has undying loyalty to her brother, going along with his decision to assault Earth after regaining their Barian identities, despite her own wishes. As a Barian, Rio possesses the ability to sense other Barians. This is shown when Girag arrived on Earth, which caused her great pain and she foretold that "they" were coming to take "the most important thing".[14] When Mizar arrived later, Rio went into a trance-like state and again said that someone was coming to destroy "the most important thing" and then describing a dragon of ill omen that would destroy everything.[15] She once more senses the presence of the Barians, and reports that they are attacking Yuma.[16] During those moments, Rio enters some sort of trance while a mysterious red or green aura appears around her. After boarding the Different Dimension Airship, Rio was able to see Astral. She expressed surprise that she could then still do so after leaving the airship.[17] Like other Barians, Rio possesses the ability to Barian Battlemorph. Rio uses an Ice Winged Beast Deck, primarily focused on Xyz Summoning "Ice Beast Zerofyne" and later her "Number 103: Ragnazero". Rio uses several cards to inflict large amounts of effect damage such as "Blizzard Falcon" and "Diamond Dust". Rio also uses cards like "Ice Fire Egg" to give her access to Ranks she cannot normally access, letting her Xyz Summon "Ice Princess Zereort". She later gains the ability to perform a Chaos Draw, giving her access to "Rank-Up-Magic - The Seventh One" to easily Special Summon her "Number C103: Ragnafinity" which she uses in combination with "Distortion Crystal" and "Zero Blade" to severely damage her opponent. Their parents are deceased when they were both only little kids and both of them are orphans. Homeless? unknown. Reginald has a terrible fear of onions and sleeps with a nightlight which Rio constantly teases him about. Both siblings are 14 years old. Whenever Rio is worried or scared, she usually clings to Reginald seeking comfort or any other forms of good feelings. Dumon is one of the Seven Barian Emperors and a close comrade of Rio Kastle, who is the human reincarnation of fellow Barian Emperor Marin. Rio is also the twin sister of Reginald "Shark" Kastle, who himself is the reincarnation of Barian Emperor Nash. So, Dumon is essentially an ally to both Rio and Reginald in their Barian forms, making their relationship one of comradeship tied by past lives. Dumons believes that rio and Reginald should come back to barian world. Don thousand is the god of barian world and Is responsible for the ressurection of the barian emperors turning them form humans to barian aliens. Abyss splash, being the one responsible for Nash and marin's reincarnations, is the ocean god of the posieden seas in their past lives.

both Rio and Reginald have found their true origins... now they must decide if they should become Nash and Marin again or fight against the barians to protect yuma and the others.