Kaze

Kozzy known as Yamikawa in the japanese version is a character in Yu-Gi-Oh! ZEXAL. He is a reformed student of Rokujuro's Duel Lodge, as well as one of the Number holders.

Entomology
"Yami" means darkness, and Kozzy was said to possess some darkness in his Duels, and had a "Number" card, which amplify the darkness in their owner's hearts.

History
In the past, Kozzy was a student at Rokujuro's Duel Lodge, but after dueling him and losing his faith, he grabbed a sword and slashed a statue of "Blade Armor Ninja", cutting it in half, after which he left the Duel Lodge and hadn't been seen since.

Yu-Gi-Oh! ZEXAL
After Yuma Tsukumo and his friends went to the Duel Lodge to help Rokujuro out, Kozzy showed up again and challenged his former master to a Duel, to which he easily won. He then ran inside and went to finish what he had previously done, cutting the Duel Statues up, but was stopped by Yuma Tsukumo who challenged him to a Duel.

As the Duel progressed, both continued to overthrow each others strategies and it was revealed that all of Kozzy's hatred caused him to become possessed by a "Number" card, or to be specific "Number 12: Crimson Shadow Armor Ninja", but he ultimately lost when Yuma Summoned "Number 39: Utopia" and defeated his "Number". He then went to slash the statue again, but was stopped by Yuma who convinced him that it was wrong, to which he apologized and began to study at the Duel Lodge again.

Deck
Kozzy uses an "Armor Ninja" Deck, capable of quick Xyz Summoning. His ace monster is "Blade Armor Ninja". Whilst possessed, he used "Crimson Shadow Armor Ninja" after "Blade" was destroyed but it was later absorbed by Astral. His cards are supported by a wide array of "Ninjitsu Art" cards.