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 of tentacles hanging down befitting his Deck theme of WATER-Attribute cards. 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 a blue-lined collar.

Personality
Ryoga's personality is similar to that of Chazz Princeton's whilst he was an elite Obelisk Blue as he believes he is the most powerful and bullies anyone whose dueling skills are weaker than his own, even taking their Decks after they lose. When Numbers possessed him, he became quite psychotic and caused destruction with his "No. 17 Revise Dragon" in the process.

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

It's mentioned that Ryoga was a participant in a national tournament, but apparently did not 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.

Manga biography
In the school that Ryoga and Yuma Tsukumo attend, Ryoga is known to be a bully, taking the Decks of his opponents when he beats them. Ryoga defeated Tetsuo and took his Deck. This caused Tetsuo's friend, Yuma to offer his pendant in exchange for the Deck back. Ryoga responded by breaking the pendant in half, so Yuma offered to Duel Ryoga himself, with his own Deck on the line.

Decks
Ryoga's Deck is a WATER-themed Beatdown/Burn Deck in which he increases the ATK of his monsters with cards such as "Drill Barnacle", "Jawsman", "No. 17 Revise Dragon" and "Aqua Jet" while also dealing Effect Damage through "Poseidon Waves", "Urchin Bomb" and "Aero Shark".