Reginald Kastle

Ryoga Kamishiro, nicknamed Shark, is a character in Yu-Gi-Oh! ZEXAL and is Yuma Tsukumo's rival.

Design
Ryoga has dark blue eyes, pale skin and dark purple hair, similar to tentacles hanging down, befitting his Deck theme of aquatic creatures as his hair is similar in appearance to an octopus. His other accessories include a spiked pendant similar to the one Yuma Tsukumo wears, as well as another pendant hanging down by a chain. He also owns a red, spiked D-Gazer. His attire includes a dark blue jacket over a black shirt and dark pants. When in his school attire, he wears a white shirt with green-lined sleeves and a collar.

Personality
Ryoga's personality is quite narcissistic as he believes that he is the number one Duelist. He flaunts this power about by taking the Decks of the people he beats, making them squirm in the process such as when he defeated Tetsuo. When he became possessed by Numbers, he became quite violent, destroying the scenery surrounding him during the Duel.

Anime biography
Ryoga challenged Yuma Tsukumo to a Duel. When the mysterious entity Astral appeared before them a new legend began.

In the past, Ryoga was a well known Duelist within the national circuit of Duels, and a favorite to win.

It's mentioned that Ryoga was a participant in a certain national tournament, but didn't win. Yuma guesses during their Duel that Ryoga's apparent obsession with making him give up was because Ryoga himself had given up on something precious to him. Judging by Ryoga's reaction, it's safe to assume that Ryoga gave up on being a pro Duelist and became a bully after losing at the national tournament.

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

Ryoga is then seen within the city square, and then begins his Duel with Yuma. Within the Duel, Ryoga quickly gains an advantage with his "Big Jaws" and "Aqua Jet" combo. He then traps 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: Leviath Dragon".

As the Duel progresses, Ryoga begins to toy with Yuma taking his Life Points down to a small fraction. But Yuma managed to come out of this, and managed to defeat Ryoga with his "Number 39: Utopia" at 5000 ATK, which knocks Ryoga out, winning Yuma the match.

Ryoga then awoke, and gave Yuma Tetsuo's Deck, and said that Yuma is different than everyone that he has faced before. He then walks off silently.

He is then later seen riding in a motorbike, after Yuma's Duel with Fuya Okudaira. It's a rouge motorcycle with a single thick wheel.

Anime
Ryoga's Deck consists of monstrous looking sea creatures such as sharks and krakens. He utilizes a Burn and Beatdown strategy in order to quickly gain the advantage through cards such as "Aero Shark" and "Urchin Bomb", with a focus on using Level 3 monsters to Xyz Summon Rank 3 Xyz Monsters.