Koichi Zenigata is the central police inspector relentlessly pursuing Arsène Lupin III throughout the *Lupin III* franchise. A Japanese law enforcement officer, he began with the Tokyo Metropolitan Police before transferring to Interpol to focus entirely on capturing Lupin, sparked by their initial encounter during Zenigata's chase of Fujiko Mine in New York. Originally named Heiji Zenigata VII to denote descent from the fictional coin-throwing detective Zenigata Heiji, this lineage was later minimized and his name simplified to Koichi Zenigata. His character is inspired by Inspector Ganimard from Maurice Leblanc's original Lupin novels.

Zenigata's personality revolves around an obsessive dedication to apprehending Lupin, shaping his entire existence. This pursuit drives him to be energetic, short-tempered, and single-minded, though his portrayal shifts across media: early manga and Part 1 anime depict a more ruthless, corruptible, and violent figure, while later anime (Parts 2, 3, TV specials) highlight comedic, bumbling, or affable traits. Consistent elements include a strong sense of justice, resistance to bribery, emotional sensitivity often leading to tears, and occasional introspection about his choices. His obsession damages personal relationships, with hints of a failed marriage and a daughter named Toshiko mentioned solely in *The Mystery of Mamo*, though other episodes contradict this by showing no family. He exhibits messy habits and occasional binge eating or drinking during low periods.

His dynamic with Lupin is complex, marked by relentless pursuit alongside a mutual, though unspoken, respect. Zenigata insists only he should capture or kill Lupin, reacting with profound grief or loss of purpose when Lupin appears dead, like his retirement to a monastery in *The Fuma Conspiracy*. Conversely, he shows frustration when Lupin remains captured for long stretches, as in Part 1 Episode 4. Their relationship involves unwritten rules against lethal force and instances of cooperation against greater threats, with Lupin sometimes aiding or avenging Zenigata. Exaggerated declarations of destiny or affection introduce romantic subtext, though Zenigata denies this.

Physically, Zenigata possesses significant endurance and combat proficiency. He demonstrates skill in judo, karate, and jitte use, marksmanship with a Colt M1911 pistol, and an uncanny ability to throw handcuffs with bola-like precision. His Lupin obsession fuels near-superhuman feats, such as waking from comas or enduring injuries upon hearing Lupin's name, and breaking through barriers during chases. As a detective, he consistently predicts Lupin's heists through behavioral analysis and research, earning Interpol respect for apprehending other criminals during his pursuits, despite frequent failures to detain Lupin long-term.

In *From Siberia with Love*, Zenigata appears in a limited capacity, pursuing Lupin during the Romanov treasure heist without unique character development, maintaining his established persona.

Visually, Zenigata's design evolves across media, notably his trench coat and fedora changing colors between anime parts (e.g., orange in Part 1, camel in Part 2, red in Part 4). He anchored the live-action *Inspector Zenigata* spin-off, exploring his professional and personal life beyond Lupin chases. Creator Monkey Punch envisioned Zenigata and Lupin as destined equals, with any series conclusion requiring their fates to remain intertwined through mutual failure, success, or aging.