Known Background: Nightblood was a member of a modern-day samurai clan, betrayed by his corrupt superior out of jealousy for a perceived affair with his wife. Poisoned and thought dying, the man now known as Nightblood spent the last few hours of his life hunting down his boss, decimating his elite guards, and eventually taking his revenge. Nightblood later collapsed and was thought dead.

Buried in an ancient ceremony, Nightblood awoke and clawed his way to freedom from his entombed casket. Gathering what funds he could and seeking out a mystic Lord from Tibet who was known to the clan for hiring out his services, Nightblood learned the poison used was an ancient potion meant to steal one's soul. However, because of his unknown superhuman potential, the poison triggered his powers and brought about his resurrection. The effects of the poison had also turned his skin white. Obsessed with becoming a living engine of vengeance, he underwent a mystical transformation wherein metal claws were grafted to his skeleton, allowing him to extend three claws from each wrist.

Seeing what greed and corruption did to his former master, Nightblood decided to take it upon himself to battle the forces of the criminal underworld. Realizing that he must begin anew, he traveled across the Pacific to the United States, drawn to the mystical energies active within the city of San Francisco. He stayed there for for several years, working under the cover of darkness to fight evil, but after his encounter with the fight clubs and being marooned at sea, he soon met Avatar and was convinced to channel that vengeance into a desire to protect parahumans from those that would eventually seek them out for destruction.