Ichiyou Higuchi serves as a Port Mafia operative and self-appointed bodyguard to Ryuunosuke Akutagawa. Her appearance includes honey-blonde hair typically in a messy bun, deep brown eyes, and a professional wardrobe featuring an unbuttoned black pantsuit with rectangular blue sunglasses; undercover missions prompt a neater hairstyle and fully fastened attire. Documented heights list her as either 159 cm or 167 cm. Personality-wise, Higuchi pairs ruthless combat efficiency with deep-seated insecurity about her mafia standing. She exhibits obsessive, one-sided devotion to Akutagawa, enduring his mistreatment and declarations of her being "unnecessary" while protecting him relentlessly. Though proficient in lethal operations, impulsiveness and self-doubt trigger panic-induced failures, like disregarding capture orders or launching reckless attacks. Colleagues doubt her suitability, citing stress-induced clumsiness, yet she displays fierce resolve when allies are threatened—balancing flaws with professionalism and bravery. No supernatural ability is confirmed, clarified in official materials despite early ambiguous listings. She compensates with exceptional firearms mastery, employing pistols and submachine guns to eliminate groups. Her skill allows brief resistance against powered foes, though she usually requires support to prevail. Background details remain sparse: she joined the Port Mafia for undisclosed reasons and lives with a younger sister, mentioned once in manga. As Akutagawa’s deputy in the Black Lizard unit, she assumes temporary command when he falls comatose but faces insubordination over her perceived lack of intimidation. This ignites her rogue mission to rescue him after his abduction. Outmatched and wounded, she nearly dies until Black Lizard intervenes, earning their respect through sheer determination. Akutagawa later thanks her—his first acknowledgment—marking a turning point. During the "Decay of the Angel" arc, Akutagawa—now a vampire—bites and transforms Higuchi. As a vampire, she attacks allies like Gin Akutagawa and Ryuro Hirotsu with heightened aggression. Outside combat, she comically insists Gin address her as "sister-in-law" and retaliates against enemies through petty acts like mailing excessive cash-on-delivery packages, revealing an awkward, lighter side beneath her mafia role.