Kyoushirou Kokujou

A self-proclaimed "evil genius" and another of Shobu's rivals throughout the series. Other characters make fun of his outlandishly styled long hair and all-black leather outfit. He uses a Darkness Civilization Deck. He has earned the nickname "Black Death," because of his relentless tactics. He became evil because people say he can not be a kaijudo master. In Season 2 he helps Shobu to defeat the P.L.O.O.P.s. In Season 3 he defeated Mimi but lost to Yumama in the semifinals. His ultimate cards are Dorballom Lord of Demons, Ballom Master of Death , Daidalos General of Fury, Olgate Nightmare Samurai, Deathliger Lion of Chaos and most recently, Demon Lord Ballom Emperor.

(Source: Wikipedia)