Ichiyō Higuchi operates within the Port Mafia as a short young woman with blonde hair typically secured in a messy bun and deep brown eyes. Her standard outfit is an unbuttoned black suit paired with rectangular blue sunglasses. During deceptions, she adopts a polished guise—hair neatly brushed, suit buttoned, and sunglasses removed. After a vampire transformation triggered by Ryūnosuke Akutagawa's bite, her eyes turn fully black without pupils, and her hair becomes disheveled. Her personality merges ruthless efficiency in Port Mafia tasks with persistent insecurity and self-doubt. She exhibits zero tolerance toward enemies and minimal compassion during operations. Internally, she questions her place in the organization and has repeatedly considered departure. Under pressure, she acts impulsively, sometimes breaching orders, while her demeanor oscillates between icy composure and overt stress. Despite these conflicts, she displays unwavering resolve, bravery, and professionalism, never forsaking endangered allies. Her most defining characteristic is obsessive loyalty to Akutagawa, whom she shields unconditionally despite enduring his verbal and physical abuse—including dismissals of her as "unnecessary." This devotion overrides protocol, driving choices that prioritize his safety. No supernatural ability is confirmed for Higuchi, with records listing it ambiguously. She compensates with elite firearms mastery, eliminating groups using pistols and submachine guns—often dual-wielded. Her background includes undisclosed reasons for joining the Port Mafia. She resides with her younger sister, though broader family context is absent. As Akutagawa’s subordinate, she commands the Black Lizard squad but initially faces skepticism due to lacking his feared reputation. Key developments include leading a failed trap against the Armed Detective Agency by posing as a client, provoking Akutagawa’s intervention and criticism. After rescuing him from severe battle injuries, she faces Port Mafia leader Ōgai Mori’s insinuations about her misfit status. When rivals capture Akutagawa, she disobeys orders for a solo rescue. Outmatched and wounded, her tenacity earns the Black Lizard’s respect, and they aid in securing Akutagawa’s survival—prompting rare gratitude from him. Later, she collaborates with Gin Akutagawa to track Osamu Dazai, delivering Mori’s leadership offer while condemning Dazai’s perceived betrayal of his violent legacy.