Kaiou

Kaiou is the First Rashou. He proclaims himself to be the Creator of the New Century and the Demon Kaiou. Kaiou is the elder blood brother of Raou and Toki, who remained in Asura after his brothers left the country when they were children. He bears a strong resemblance to Raou, only with an x-shaped scar on his face. Kaiou is characterized as the strongest warrior of Asura and is the only other character besides Souther to brutally defeat Kenshirou following their initial encounter. He wears a specially constructed armor which allows him to control his evil aura. He hates the main Hokuto bloodline, from which Ken and Hyou are descended, due to the fact that he was forced to play a subordinate role to Hyou by Jukei, despite possessing superior skills. Kaiou is the last major villain in the manga (there are others after him) and the final opponent Kenshirou faces in the TV series.

(Source: Wikipedia)