Sigma fights as one of the "Cosmo Warriors" in the Sacred Sword War, allied with Kojirou, Musashi, Ryouma, and Soushi Date. He hails from the previous Sacred Sword War, fought 4,000 years before the events of Seiken Sensou-hen, where he was sealed away to await the conflict's return.

He reawakens precisely when the Sacred Sword War resurges, joining the current generation of warriors against the Chaos faction. Sigma wields the Sacred Sword Byakurouken, engaging directly in battles against the Chaos Warriors Nero, Oz, Jackal, Shura, and the Chaos Emperor.

As an ancient warrior, his background suggests familiarity with the conflict's cyclical nature, tied to Saṃsāra—the Buddhist concept of karmic rebirth and destiny. His participation contributes to the Sacred Sword War arc's theme of predestined conflict.