Koichi Zenigata, an inspector with the International Criminal Police Organization (ICPO), relentlessly pursues the phantom thief Lupin III. This pursuit leads him to Japan, where he assists the Tokyo Metropolitan Police Department in safeguarding the valuable Cherry Sapphire gem. Zenigata orchestrates security and investigations alongside local law enforcement, collaborating with Inspector Megure, a fellow graduate from their police academy days. Zenigata exhibits remarkable physical resilience. He withstands a stun gun shock potent enough to incapacitate an elephant for thirty minutes, regaining consciousness after only thirty seconds, driven solely by his intense focus on capturing Lupin. Despite Zenigata implementing stringent precautions, Lupin successfully deceives him by disguising himself as Detective Takagi, enabling the theft of the Cherry Sapphire. His investigative approach prioritizes direct confrontation and unwavering persistence. Zenigata maintains operational authority even while working with assisting officers like Miwako Sato and Wataru Takagi. His efforts contribute significantly to thwarting a larger conspiracy involving the illicit trade of a rare mineral with military applications, though Lupin ultimately escapes custody as the case concludes. Throughout the incident, Zenigata's professional conduct remains strictly focused. He refrains from personal commentary unrelated to the investigation and immediately resumes his pursuit of Lupin following the resolution of the primary case.