Master Scythe, born Helmut von Giuseppe, is a German scientist possessing a P.H.D. in psychology and brain development. He presents as a tall man typically seen wearing glasses and a lab coat. Originally a researcher, he entered the criminal underworld adopting the alias Scythe Master.

He specializes in fashioning assassins through a precise regimen of memory erasure via drugs and hypnotherapy, coupled with psychological conditioning designed to eradicate emotional resistance to killing. His creations, including the assassins Ein, Zwei, Drei, and the Zahlenschwestern (Number Sisters), are viewed purely as expendable tools. He styles himself their "puppet master."

Exhibiting sadistic tendencies and delusions of grandeur, Scythe Master perceives the world as his experimental stage, taking perverse satisfaction in refining his methods across successive subjects and noting their psychological differences. Within the criminal organization Inferno, he serves under executive Claudia McCunnen, though he secretly resents her authority. His collaboration with Inferno serves only to advance his personal objectives: expanding his influence and testing his assassin-manufacturing techniques.

His trajectory involves betraying Inferno following the initial phase of Zwei's training, escaping the organization to pursue his own agenda. He later returns seeking revenge against Claudia and aiming to reclaim control over his creations, particularly Ein, whose growing independence—fueled by Zwei's influence—directly threatens his authority. This quest for dominance culminates in direct confrontations with Inferno's leadership.

Scythe Master operates with utter disregard for the autonomy or suffering of his subjects, dismissing their psychological trauma as irrelevant to their function as weapons. His actions consistently reflect his self-aggrandizing worldview and relentless desire for dominance over the assassins he manufactures.