Kakihara is the central antagonist of Ichi the Killer, a figure whose extreme psychology drives the entire narrative forward. His background is deeply embedded in the yakuza underworld, where he serves as a high-ranking enforcer for the Anjo gang. His loyalty to his boss, Anjo, is not born of traditional honor or duty, but from a deeply personal and perverse form of admiration. Allusions within the story suggest that Kakihara is utterly in awe of Anjo specifically because of the violence the boss can inflict; the long, prominent scars that mark Kakihara's face are implied to be gifts from his superior, representing the ultimate bond between them. This fixation transforms the disappearance of his beloved sadist boss into an all-consuming obsession.

In terms of personality, Kakihara is a study in controlled chaos and profound deviance. He is a classic sadomasochist who experiences pleasure not just from inflicting pain on others, but equally, if not more so, from receiving it. He is described as cold, calculating, and utterly fearless, with a calm and methodical demeanor that makes his acts of extreme brutality even more unsettling. His cruelty is not impulsive rage; it is a precise, almost artistic practice that he pursues with the enthusiasm of a connoisseur. Beneath this lies a profound death wish; he is a man living on borrowed time, searching for a person powerful and vicious enough to deliver him the ultimate sensation: a worthy death. He is not a typical villain driven by greed or power, but by an insatiable craving for sensory extremes.

Kakihara's primary motivation is simple yet twisted: to find Ichi. Once he learns that Ichi was responsible for the disappearance of Boss Anjo, his quest for his master transforms into a passionate hunt for the killer. He reasons that any man capable of causing such harm to the sadist he adored must be capable of inflicting unimaginable pain, and therefore, unimaginable pleasure. His role in the story is that of the relentless pursuer. While the mysterious and manipulated Ichi serves as a weapon for the puppet master Jijii, Kakihara is the active agent, carving a bloody path through the yakuza underworld, torturing anyone who might have information and throwing the delicate balance of gang politics into violent disarray.

His key relationships are defined by his singular fixation. The most important is, by far, the one he never truly has: his relationship with Ichi. Throughout the film, he builds Ichi up in his mind as a savior-like figure who can grant his death wish, leading to a perverse sense of admiration and a desire for a one-on-one confrontation that borders on a twisted form of love. In the absence of his boss, his relationship with his own yakuza subordinates is one of authority and loyalty, though they are often horrified by his methods. Notably, he also has a fleeting relationship with a woman named Karen, whom he attempts to instruct in the humane treatment of masochists. However, when she fails to elicit the genuine thrill of mortal danger within him, he coldly dismisses her, demonstrating that no ordinary person can fulfill his needs.

Kakihara does not undergo a traditional emotional development or redemption arc. Instead, his trajectory is a steady, unfaltering march toward his goal. His development is external, manifested through his escalating methods and the physical sacrifices he makes. After torturing an innocent man based on false information, he upholds a bizarre code by severing the tip of his own tongue with a sword as an act of apology, a gruesome ritual that only intensifies his drive. As the film progresses, his obsession sharpens into a single-minded focus until the final confrontation, where his psychological state reaches a fever pitch.

Kakihara is notable for a range of physical and psychological abilities. Physically, he is a capable and brutal fighter, though his most notable tools are of the torturer, not the warrior. He favors skewers and needles to elicit information and pleasure from his victims. His most iconic feature is his Glasgow smile: the corners of his mouth are slit open to his cheeks, held together by metal rings. This piercing allows him to open his mouth to an unnaturally wide degree, an ability he uses to dramatic effect. He is also identifiable by his signature blonde hair and stylish, custom-made suits. However, his most defining ability is his extreme tolerance for pain. He does not merely endure injury; he actively seeks it, using acts of self-mutilation and the reception of violence as a path to a euphoric state, making him an utterly unpredictable and terrifying opponent.