Inspector Koichi Zenigata is a Japanese officer working for the International Criminal Police Organization, commonly known as Interpol. Before joining Interpol, he served with the Tokyo Metropolitan Police Department. His primary and all-consuming mission is the capture of the master thief Arsène Lupin III, a goal that came to define his entire professional life after their first encounter.

In appearance, Zenigata is typically portrayed as a middle-aged man with dark hair and a sturdy build. His iconic uniform, worn across nearly all his appearances, consists of a khaki trench coat, a dark suit, and a classic fedora hat. His personal living and working spaces, such as his apartment and office desk, are famously cluttered and untidy, a consequence of his relentless, globe-trotting pursuit which leaves him little time for domestic order.

Personality-wise, Zenigata is a study in contrasts. He is driven by an unshakable and old-fashioned sense of justice and is widely respected within Interpol for his skill in dismantling criminal organizations and capturing dangerous felons. He is notably resistant to bribery and corruption, a trait that sets him apart from many other law enforcement officers in his world. However, this competent and serious side is often juxtaposed with a bumbling, impulsive, and overzealous demeanor when he is in direct pursuit of Lupin. This obsession frequently leads him into slapstick situations and humiliating defeats, yet his tenacity never wavers. He is an emotionally sensitive man who is not afraid to weep openly, whether from frustration, relief, or joy, especially concerning Lupin. He is also known to go on heavy drinking binges when in a state of deep depression, such as after being suspended from duty.

Zenigata's core motivation is not merely to enforce the law but to personally be the one to arrest Lupin III. This singular focus has put a strain on his personal life; it is mentioned in some stories that he has a daughter, Toshiko, and that his marriage failed due to his obsession. He has little life outside of the chase, and on the rare occasions when he believes Lupin to be dead, he experiences a profound loss of purpose, sometimes leading him to retire or, in one instance, become a Buddhist monk. Conversely, when he does succeed in capturing Lupin, he can become frustrated if the thief does not attempt an escape, suggesting that he values the pursuit as much as the arrest itself.

His role in the story is that of the eternal pursuer, the primary antagonist who is never quite able to achieve his goal. Despite this, he is a figure of great respect and serves as a moral anchor. He often finds himself in a complex, unspoken alliance with Lupin and his gang when a greater evil or a common threat emerges, temporarily setting aside their rivalry to work together.

The most significant relationship in Zenigata's life is with his quarry, Lupin III. Their dynamic transcends the typical cop-and-criminal relationship, evolving into a deep, mutual respect that borders on friendship. Zenigata believes that no one else has the right to kill or even capture Lupin; that privilege belongs solely to him. Lupin, for his part, often greets the inspector with mock affection and the nickname "Pops" (or "Totsan"). He has frequently gone out of his way to save Zenigata's life and has avenged him when he thought the inspector was killed. While Zenigata is also interested in capturing Lupin's associates, Daisuke Jigen, Goemon Ishikawa XIII, and Fujiko Mine, his focus is almost entirely on Lupin himself. Jigen, in particular, is known to have a healthy fear of Zenigata's capabilities.

Across the long-running franchise, Zenigata has shown notable development. In his earliest depictions, he was a more ruthless, cynical, and even corrupt officer who was willing to bend the rules to get results. Over time, he has mellowed into a more loveable, though still eccentric, figure whose respect for Lupin redeemed his harsher qualities. While he remains a "crouching moron, hidden badass," his competence as a detective has been increasingly highlighted, showing that his failures to catch Lupin are due more to the thief's supernatural luck and skill than any lack of ability on the inspector's part.

Zenigata possesses a formidable array of abilities that mark him as an exceptional police officer. His most famous and unique skill is the near-superhuman accuracy with which he throws a pair of handcuffs attached to a rope, using them almost like a bola to capture fleeing criminals from a distance. He is highly proficient in hand-to-hand combat, including judo and karate, and has been shown to single-handedly incapacitate groups of armed assailants. He is also an expert marksman with his signature Colt M1911 pistol. Beyond his physical prowess, Zenigata's obsession grants him seemingly superhuman endurance and resilience. He has been known to break down reinforced doors through sheer rage, and, in some stories, he has willed himself back from a coma or awakened moments after being hit with a tranquilizer that could subdue an elephant for half an hour. He is also a skilled inventor, having created unique gadgets like the "Zenigetchas," thumbcuffs that even Lupin could not escape without help.

Regarding the specific film The Legend of the Gold of Babylon, no information is available.