Himeno is a supporting character and a Public Safety Devil Hunter who serves as a senior member of Special Division 4. She is instantly recognizable by her black eyepatch, which covers her right eye, and her short, dark, slightly unkempt hair. A tall and slim young woman with a voluptuous build, she is typically seen wearing her division's formal suit with a black tie. Her most defining physical feature is the eyepatch, a permanent reminder of the contract she made with her devil.

Personality-wise, Himeno presents herself as a mature, upbeat, and experienced superior. She is capable of remaining calm under extreme stress, such as when her team is trapped by the Eternity Devil, and she is known to take unorthodox approaches to motivate her subordinates, like offering Denji a kiss to encourage him in battle. She is efficient and blunt in her duties, not hesitating to use her devil's power even against seemingly insignificant threats. Beneath this cheerful and carefree facade, however, Himeno harbors a deeply pessimistic worldview. Having witnessed multiple partners die in the line of duty, she has developed a fatalistic acceptance that Devil Hunters rarely live long lives. This trauma leads to her reliance on vices; she is a chain smoker and a heavy drinker, often becoming wild when intoxicated. Her master, Kishibe, taught her that the most successful Devil Hunters are those who have a few screws loose, a philosophy she has internalized, which explains her unpredictable and sometimes morally gray actions.

Himeno's primary motivation is the protection of her current partner, Aki Hayakawa. Having lost five partners before him, she is desperate to prevent another death and will go to extreme lengths, including betraying others, to ensure his safety. She has developed strong romantic feelings for Aki, valuing his normalcy and cool demeanor, and she sees Makima as a rival for his affection. Her role in the story is that of a mentor and senior hunter to the new recruits, including Denji, Power, Kobeni Higashiyama, and Hirokazu Arai. While initially skeptical of Denji, seeing him as a potential sacrifice, she comes to respect his chaotic and unpredictable nature, believing he might have what it takes to defeat the Gun Devil. After a drunken incident where she attempts to seduce him, she and Denji form a friendship and a secret alliance to help each other pursue their respective romantic interests.

Key relationships define her character. Her bond with Aki is the most significant; she introduced him to smoking, trained him, and became emotionally dependent on him. With Denji, her relationship evolves from using him as a tool to genuine camaraderie. She harbors a deep distrust of Makima, whom she sees as a dangerous and manipulative figure. Her mentor, Kishibe, is a fellow heavy drinker who imparted the harsh lessons of their profession onto her. She also shows a caring side to her other subordinates, like Kobeni, while also being stern enough to physically subdue them when they become a danger to the group.

Throughout her time in the story, Himeno experiences notable development. She moves from viewing Denji as expendable to becoming his supporter and friend. She also transitions from a hunter who is paralyzed by the fear of losing her partner to one who makes the ultimate sacrifice to save him and her other comrades. Her notable abilities stem from her contract with the Ghost Devil, for which she sacrificed her right eye. This contract allows her to summon and control the invisible, intangible, and immensely strong right arm of the Ghost Devil. She is also a skilled hand-to-hand combatant, capable of disabling a fellow hunter with a single strike. In a desperate final act, she offers her entire body to the Ghost Devil in exchange for its full power, summoning its complete form to overwhelm her enemies before she vanishes, leaving only her uniform and eyepatch behind.