Souga hails from the Land of Asura, a childhood companion of Raoh. He masters the devastating Sūzan Senpū Kyaku, the Songshan Whirlwind Kick. Alongside his sister Reina, he leaves their homeland to aid Raoh's campaign to dominate the wasteland. Within Raoh's King of Fists Army, Souga serves as the crucial military strategist. His driving ambition is to unite Raoh with his Hokuto brothers, Toki and Kenshiro, securing ultimate supremacy.

Stricken by terminal illness, Souga engineers a deceptive assassination plot against Raoh to discipline complacent troops. He deliberately meets his end by Raoh's hand during this staged event. Souga's pre-death letter later reveals the conspiracy's truth, including Raoh's prior knowledge and cooperation, to Reina.

The Ten no Haoh spin-off reveals Souga earned the epithet "Souga the Swift Foot" (韋駄天のソウガ, Idaten no Sōga) early in Raoh's rise. Escaping Cassandra with Raoh and Reina, Souga triggers a trap, suffering a severe injury and losing his right leg, leading to a mechanical prosthetic. After encountering Ryuga, Souga consciously sheds his humanity, embracing ruthless tactics to further Raoh's conquest. A later battle against Gaiya inflicts a fatal wound, leaving Souga with a prognosis of a mere two months to live.