Mr. X is the commissioner of the Scorpion Crime Syndicate. A near-fatal electrocution inflicted by Lupin III at the Scorpion-controlled Hida Speedway fueled his deep vendetta against both Lupin and Fujiko Mine. Utilizing his immense wealth, he replaced his original heavyset human body with extensive experimental cybernetic reconstruction, resulting in a metallic, robotic form.

His animosity drives him to orchestrate elaborate schemes targeting Lupin and his associates. In "Is Lupin Still Burning?", he allies with the time-manipulating Kyosuke Mamo. Together, they plot to erase Lupin from existence by altering key moments in his past. Mr. X lures Fujiko into a trap using a valuable golden statue and captures her, restraining her on a specialized torture device.

He exhibits a recurring preference for psychological and physical torture, specifically involving tickling. Activating robotic arms to administer tickle torture to Fujiko, he explicitly states his primary motivation is deriving sadistic pleasure from her suffering, not extracting information. He intends for her to endure this torment while simultaneously witnessing Lupin's erasure through Mamo's temporal manipulations.

Mr. X initiates the plot against Lupin within the alliance, while Mamo handles the time alterations. After Mamo reports capturing Lupin, Mr. X eagerly approaches to taunt his enemy. This proves a ruse; Lupin, disguised as Mamo, had subdued the actual time traveler. Lupin reveals the deception and informs Mr. X that he has been transported, along with the bound Mamo, to a prehistoric jungle populated by dinosaurs, constituting his ultimate fate.