Koichi Zenigata is a Japanese police inspector with Interpol, originally from the Tokyo Metropolitan Police Department. His life revolves entirely around capturing the international thief Lupin III, an obsession consuming his professional and personal existence. This pursuit began when he transferred to Interpol specifically to apprehend Lupin after their first encounter in New York during an investigation targeting Fujiko Mine and her partner. His dedication is absolute, leading him to disregard personal comfort, finances, or direct orders from superiors. Despite this singular focus, he maintains a strong, old-fashioned sense of justice and honor, resisting bribery and corruption, though early depictions in Part I and *The Woman Called Fujiko Mine* show a more opportunistic, morally ambiguous side. Zenigata exhibits a complex personality duality. He is respected within Interpol for exceptional crime-solving skills and a track record of apprehending numerous criminals beyond Lupin, often unintentionally during his chases. This collateral success justifies his employment despite repeated failures to capture his primary target. He demonstrates moments of keen deductive reasoning and strategic planning, inventing specialized gadgets like thumb cuffs and unbreakable handcuff chains tailored for Lupin. Yet, he frequently displays impulsive, overzealous behavior bordering on bumbling, especially when directly confronting Lupin, manifesting in outbursts of rage, signature yells of "LUPIIIIIIIIIIN!", and susceptibility to Lupin's deceptions. He is emotionally sensitive, prone to weeping during perceived kindness from Lupin or relief upon discovering Lupin survived mortal peril. His personal life is neglected due to his obsession; family references are inconsistent, mentioning a daughter Toshiko in *The Mystery of Mamo* but later stating he has no family in Part II. Romantic relationships are hindered by his single-mindedness, and his living spaces are perpetually messy. His relationship with Lupin transcends a simple cat-and-mouse dynamic. While sworn enemies, an unwritten understanding exists where neither attempts to kill the other. Zenigata harbors a deep-seated belief that only he has the right to capture Lupin, reacting with outrage or grief if others threaten or apparently succeed in killing him. Instances where Lupin appears dead leave Zenigata despondent and purposeless, leading to drastic actions like temporary retirement and becoming a monk in *The Fuma Conspiracy*. Conversely, Lupin demonstrates respect for Zenigata's tenacity, occasionally aiding or avenging him when threatened by third parties. Zenigata reluctantly acknowledges a form of mutual dependence, sometimes displaying surprising affection towards Lupin, though he vehemently denies deeper feelings despite running jokes suggesting otherwise. He is never truly satisfied when Lupin is captured, as shown by his frustration in Part I when Lupin remained imprisoned, wishing for his escape so the chase could resume. Physically, Zenigata maintains good condition for his age, proficient in judo, karate, and jitte combat, capable of dispatching multiple attackers. His marksmanship with his Colt M1911 pistol is reliable, but his signature skill is near-superhuman accuracy throwing handcuffs like a bola. His obsession fuels seemingly impossible physical feats during chases, like breaking down doors in intense focus or awakening from comas upon hearing Lupin's name. His appearance is iconic: a middle-aged Japanese man of average height with dark hair, often styled in a flat-top or comb-over, and a pronounced cleft chin. His attire consistently features a trench coat, suit, and fedora, though colors vary across series. He is only slightly taller than Lupin, allowing for mutual disguises. Zenigata's character undergoes development across the franchise. Early manga and Part I portray him as more ruthless, corrupt, violent, and self-serving. A shift occurs around Part I, Episode 14, where he mellows into a more affable, endearingly awkward, and overtly justice-driven figure. Subsequent portrayals vary in balancing his serious competence with comedic overzealousness: *The Woman Called Fujiko Mine* and related spinoffs depict him sterner and more cynical, while the Red and Pink series and many TV specials emphasize his goofier, good-natured side. Later series like Part 4 and Part 5 attempt a more balanced integration of these traits. His commitment remains unwavering regardless of official status; he resigns or continues investigations while suspended when ordered to stop chasing Lupin, declaring he will pursue him as a private citizen.