Inspector Koichi Zenigata stands as the perennial rival to Lupin III within their franchise, embodying a dynamic akin to a "human Tom and Jerry." His character was conceived such that any definitive conclusion to the Lupin III saga necessitates both figures ending as equals, whether through shared failure, shared success, or shared aging. Originally introduced as Heiji Zenigata VII, a direct descendant of the fictional coin-throwing detective Heiji Zenigata, his lineage was later downplayed, and he was renamed Koichi Zenigata. His signature technique of throwing handcuffs modernizes his ancestor's coin-based weaponry. Zenigata's true literary counterpart is Inspector Ganimard from Maurice Leblanc's original Arsène Lupin novels. Physically, Zenigata appears as a middle-aged Japanese man of average height and muscular build, often depicted slightly taller than Lupin, aiding their frequent impersonations of each other. His visual design evolved across media, with early iterations showing darker, red-toned skin that lightened over time. He consistently wears a trench coat, suit, and fedora, though the colors shift per series: orange in Part 1, camel in Part 2, light green in Part 3, red in Part 4, with variations later. In *The Castle of Cagliostro*, his attire is a brown suit with green pants, a red tie, and he notably wears a corset for back support. Zenigata's personality blends competence with comedic obsession. A respected Interpol inspector renowned for exposing security flaws and dismantling criminal networks, he nonetheless faces criticism from superiors over his singular fixation on capturing Lupin. He possesses a strong sense of justice, refusing bribes and confronting Interpol corruption. His pursuit verges on pathological; Lupin's absence or presumed death triggers insomnia, depression, or a loss of purpose, as shown when he briefly became a monk in *The Fuma Conspiracy*. Despite their rivalry, Zenigata maintains a grudging respect for Lupin and actively prevents others from killing or capturing him, asserting only he holds that right. This dynamic sometimes forces them into temporary alliances against greater threats, like their collaboration against a counterfeiting ring in *The Castle of Cagliostro*. Impulsive and bound by old-fashioned honor, he frequently clashes with authority, yet continues operating independently when suspended or resigned, seen in *Tokyo Crisis* and *The Mystery of Mamo*. He is emotionally expressive, weeping during acts of kindness toward him or when relieved at Lupin's survival. His obsession prevents long-term relationships, though *The Mystery of Mamo* briefly mentions a daughter, Toshiko. His personal habits include messy living spaces, occasional binge eating (favoring ramen or burgers), and depressive drinking. Zenigata demonstrates exceptional physical prowess and deduction. He is highly skilled in judo, karate, and jitte combat, capable of effortlessly subduing multiple attackers. His marksmanship with a Colt M1911 and uncanny accuracy with thrown handcuffs are signature abilities. When consumed by his chase, he performs superhuman feats, such as biting through handcuffs or reviving from a coma upon hearing Lupin's name. He also invents gadgets like unbreakable "Zenigetcha" thumb cuffs and train couplings, plus the "Lupin Catcher" detection device. In *Lupin III: The Columbus Files*, Zenigata appears as the relentless pursuer, leading a Japanese police SWAT team in the hunt for Lupin, deploying inventive tactics while maintaining his trademark focus, though the narrative centers on Lupin and Fujiko.