Organized crime is rampant in America with frequent street assassinations, thanks to Inferno, a notorious company that operates through their indestructible human weapon, "Phantom." Meanwhile, a Japanese tourist witnesses one of Phantom's murders and takes refuge in an isolated building. However, Phantom, who goes by the pseudonym "Scythe Master" and is actually a young woman called Ein, discovers the tourist and captures him.
Through brainwashing, the tourist is now known as "Zwei" and becomes a mere tool of Inferno, completely stripped of his past memories. Trapped in a world of deceit, betrayal, and brutality, Zwei struggles to survive while searching for his true identity and a way out from the constant threat of death.
