Inspector Basilio, known as Zenigata, is a determined officer of Interpol who has dedicated his life to the pursuit of the master thief Lupin III. His background is rooted in the Tokyo Metropolitan Police, where he first built a reputation as a capable and relentless investigator, before joining Interpol to gain the international jurisdiction necessary to chase Lupin across the globe. This singular focus, however, has come at a significant personal cost. His all-consuming obsession with capturing his quarry has strained his family relationships, with passing references to a daughter and a marriage that has suffered due to his absence.

The personality of Inspector Basilio is defined by a compelling contradiction. He is at once a world-class detective and a frequently bumbling comic figure. His fellow officers hold him in high regard as an expert criminal catcher, a man who has taken down countless gangs and solved myriad cases. Yet, when faced with Lupin, his obsessive nature and impulsive drive often lead to spectacular and humorous failures. He possesses an old-fashioned, unwavering sense of justice and is fiercely resistant to corruption, often taking offense when someone attempts to bribe him. Despite his tough exterior, he has a vulnerable side, occasionally succumbing to deep depression and heavy drinking when his pursuit hits a dead end or he is suspended from the force. This emotional vulnerability also extends to his strange relationship with Lupin; on the rare occasions when the thief appears to have died, Zenigata has been known to genuinely mourn him.

His primary role in the story is that of the indefatigable foil. He serves as the law that eternally chases the charming outlaw, creating the central tension and comedic dynamic of the series. However, his role is not simply that of a pursuer. In many situations where a greater evil emerges, Zenigata becomes a reluctant ally to Lupin and his gang. Their rivalry operates on a deeper level of mutual respect; Zenigata wants to be the one to capture Lupin, and no one else. He has even been known to defy direct orders from his superiors at Interpol to continue his mission, believing that his personal code of justice supersedes bureaucratic protocol. This key relationship with Lupin is the most complex in his life, built on a foundation of professional opposition and grudging, unspoken friendship, with Lupin frequently and affectionately referring to him by the nickname Pops. His interactions with the other members of the gang—Jigen, Goemon, and Fujiko—are less personal, though he is certainly capable of apprehending them as a means to get to their leader.

Throughout the many adventures of Lupin the Third, particularly in the third part of the anime series, Zenigata demonstrates a wide array of notable abilities that prove he is far more than just a persistent nuisance. His signature technique is the masterful throwing of his handcuffs, which he can hurl with unerring accuracy over long distances, often attaching them to a rope or a bola-like cord to ensnare his target. He is a formidable hand-to-hand combatant, proficient in judo and karate, and has been shown to single-handedly incapacitate groups of armed assailants without much effort. His investigative skills are top-notch, and his cleverness shines through in the various gadgets he invents specifically to counter Lupin, such as special glue traps and unbreakable thumbcuffs. Perhaps his most astonishing ability is his sheer tenacity, which borders on the superhuman. His obsession is so powerful that he has been shown to recover from a flatlined state simply upon hearing Lupins name, awakening mere seconds after being hit with a powerful tranquilizer, and performing feats of immense strength while in a blind rage. He is a living example of the idea that a dedicated heart can push the human body to its absolute limit in the name of justice.