Koichi Zenigata (usually called Inspector Zenigata) is an incredibly talented, yet often bumbling police officer who has made it his life's goal to capture Lupin III.
Inspector Zenigata was conceived as Lupin's arch rival to create a "human Tom and Jerry".
Monkey Punch has said that he believes the Lupin III story can never end but that if he had to, both Zenigata and Lupin would have to end as equals. They would either both fail, both win or both get very old. At the end of the second manga written by Monkey Punch, Zenigata succeeds at killing Lupin and his gang, but because Lupin is meaner in the manga, he has it coming to him, whereas in the anime he's more chivalrous to those in need, which means Zenigata's actions towards Lupin are a little more lenient.
Zenigata is impulsive and temperamental, but a competent police officer. His "cowboy cop" tendencies, however, are met with disapproval by Japan's ICPO delegate when he tries to get the organization to prosecute Count Cagliostro.
Though Zenigata has failed many times to catch Lupin, many younger than him have not come as close.
Lupin describes him in the film as "truly a child of the Shoowa period, a man totally devoted to his work."
In The Castle of Cagliostro, while he is still impulsive and loses his temper, he makes sure not to do so in front of Count Cagliostro, who greets him with rudeness, racism and dismissal, and tries to stay professional.
The film shows Zenigata to be highly patriotic. He prays for the soul of a deceased Japanese spy, and when he and Fujiko charge into the printing press, he carries a jitte, a traditional Japanese bludgeon.
He shows his goofy and eager side when, Fujiko's help, he pretends to "discover" the counterfeit printing presses, through Fujiko's live camera.
He reciprocates kindness when it is given to him, even grudgingly so from the likes of Lupin.
Zenigata is a muscular, square-jawed, ruddy-skinned man of about average height (5'10''), with black hair cropped into a flat-top haircut and black eyes. He has a fairly similar build to Lupin, which makes it easier for the latter to impersonate him. He is also more handsome in The Castle of Cagliostro than in the manga and some of the anime series. In this film, he wears a brown suit with green pants and a red tie.
As shown in the anime series, Zenigata views Lupin as much of a rival as he does a friend, and, rather surprisingly, will come to him in times of need. Here he still views Lupin as something of a threat and vows to arrest him at some point, but circumstances here have forced them to work together. When they discover the printing press, they form a temporary truce. This incarnation, as with some others, cares about Lupin; when he is thrown out of the Count's autogyro, he hopes aloud that Lupin doesn't die before he arrests him. At the end of the film, he still fails to catch up to Lupin, and explains to Clarisse that he stole "her heart", before going off in pursuit of Lupin as usual.
Zenigata views the Count as a rude, condescending, stuck-up, racist, privileged man, and that's before he learns the truth about him. He takes care to stay professional in front of him and his staff, knowing the delicacy of his job situation.
Zenigata only sees the innocent and gentle Clarisse for a few seconds, but is kind and courteous towards her.
- The Streamline dub incorrectly gives his name as "Keibu", which is in fact his title. The confusion stems from the fact that, like Lupin and Jigen, he is seldom if ever addressed by his given name.
- The Streamline dub omits all references to Zenigata's nationality, for example Jigen identifying his vehicle as a Japanese police car.
The kanji of his given name, Koichi, means "Happy one". Zenigata means "Monkey-shaped".