Moutoku Sousou is the main antagonist of Ikki Tousen: Dragon Destiny. The current Motouku Sousou is actually not evil, but his namesake, a dragon spirit residing inside him, is.
He was voiced by Dan Green.
In Chinese legend, Sousou was a ruthless warlord. Like the original Hakufu and Gentoku, he was so tenacious that he returned as a dragon spirit, with the element of fire.
The current Sousou, leader of Kyosho Academy, was competing with Nanyo and Seito for power after the death of Rakuyo's leader, Chuuei Toutaku. During this time, Dragon Sousou was beginning to manipulate him, as were Bunwa Kaku, Hokou Kakuka, and Chuutatsu Shibai, who all wanted Dragon Sousou to awaken (Shibai wanting to start a war, and Kakuka wanting to use the Dragon Jade to control him and rule alongside him). After Kaku and Kakuka arranged a Yoshu attack on Sousou and his best friend, Kakouton, Yoshu assassin Koshaji attacked them and gouged out Kakouton's left eye. This enraged Sousou and allowed his dragon to take over, who killed Koshaji.
After Kakuka was assassinated, Sousou believed Nanyo to be responsible and sent Toutotsu and his gang of Ugen High School to kill Hakufu, but they failed. Sousou told Toutotsu he didn't need him anymore, and when Toutotsu decided to kill Sousou and rule the world himself, Dragon Sousou took over and killed Toutotsu and his gang.
Dragon Sousou wanted Unchou Kan'u, to which Sousou willingly ordered her capture, hoping that if his dragon was satisfied, he would be free of him. After the Three Pillared Gods captured Kan'u, Dragon Sousou forced her to work for him. When Hakufu attacked Kyosho as revenge for an attack on Nanyo, initially Kan'u fought in Sousou's place, but when Dragon Sousou appeared, Dragon Hakufu attacked him, but he blasted Hakufu, seemingly killing her.
Realizing that Kan'u's presence would not free Sousou, but rather cause him to be consumed by his dragon, Kakouton released Kan'u. Dragon Sousou attacked and seemingly killed Kakouton as punishment (he was later revealed to still be alive at the tail end of the series). Soon after, Sousou was restrained with chains, and guarded by Kyosho fighter Kyocho while Shibai became acting leader of Kyoshou's forces.
When Nanyo and Seito formed an alliance and declared war on Kyosho, Dragon Sousou gave Shibai some of his power. After all the Kyosho fighters were defeated, Shibai, mortally wounded by Kan'u, transferred her evil powers to Sousou, destroying herself while releasing Sousou, who was taken over and completely consumed by his dragon. Dragon Sousou awakened Dragon Gentoku and tried to kill her, but she was saved by Hakufu, who was in dragon form but in complete control. Gentoku gained control over her dragon's power, and the Dragon Jade empowered Hakufu and Gentoku while weakening Dragon Sousou. Together, Hakufu and Gentoku used the power of their dragons to destroy Dragon Sousou in a flash of rainbow light.