Phantom opens in an America where mafia violence has become routine and the secret organization Inferno quietly steers many of the killings carried out in its streets. At the center of that hidden conflict is Phantom, Inferno's nearly invincible human weapon, a name that inspires fear even among criminals.
The story turns when a Japanese tourist accidentally witnesses Phantom carrying out a murder. Desperate to escape, he hides in a secluded building, but he is tracked down by Phantom herself—later revealed to be a young woman named Ein—and by Inferno's leader, Scythe Master. Rather than eliminating him, they capture him and strip away his identity through brainwashing. Reborn as Zwei, the former tourist becomes a controlled instrument of Inferno, forced to live without memories of his past.
Pulled into a world of deception, violence, and constant manipulation, Zwei struggles to survive each day while searching for a path back to the person he used to be. As he moves deeper into Inferno's shadowy network, every choice carries the threat of death, and every clue about his lost life comes at a dangerous price.