Ryūga, elder brother to Juza and Yuria, is bound to the solitary star Sirius, mirroring his lone path. He masters the Mount Tai Sirius Fist (Taizan Tenrōken), a martial art that chills adversaries to the bone before delivering lethal precision, reflecting his conviction that order in a shattered world demands iron-fisted rule.

Driven by a secret motive to save Yuria from the enigmatic "King," he enlists in Raoh’s army, seeing the warlord’s conquests as a tool to impose structure on chaos. When Juza reveals Yuria’s fate, Ryūga discards his personal quest yet remains loyal to Raoh, redirecting his zeal toward grander schemes of dominance.

His past, unveiled through Yuria’s memories, depicts a shared childhood marked by familial bonds and his role as protector before nuclear ruin reshaped their lives. Though these ties inform his choices, his methods embrace brutality over mercy.

Beyond Raoh’s wars, Ryūga clashes with Kenshiro, orchestrating battles that test both skill and wit. He kidnaps Toki, Raoh’s ailing brother, exploiting his radiation-induced frailty to lure Kenshiro into combat. Their final duel leaves Ryūga mortally wounded. With his last breath, he discloses his kinship to Yuria, conceding Kenshiro’s destiny to merge love and sorrow into a beacon for humanity.

His journey navigates the conflict between allegiance to Raoh’s vision and lingering personal ties, culminating in his acknowledgment of Kenshiro as the world’s uniting force—a warrior torn between ambition’s pull and the weight of buried kinship.