Nui Harime serves as the secondary antagonist of the story and holds the title of Grand Couturier within the Revocs Corporation. She is the one who murdered Isshin Matoi, Ryuko’s father, and took one half of the Scissor Blade, making her the primary target of Ryuko’s quest for vengeance. Nui was born from an artificial womb made of life fibers, a fact that connects her to both Ragyo Kiryuin and Ryuko, and she openly claims that Ryuko and she are sisters.

In appearance and demeanor, Nui presents a childlike, jovial, and outwardly friendly disposition. She is almost always smiling and behaves with an excessive, unsettling politeness even toward her enemies. This cheerful exterior masks a deeply sadistic and malevolent nature: she takes genuine pleasure in causing pain, chaos, and destruction, and she delights in taunting her opponents. Her motivations are rooted in a strong allegiance to Ragyo Kiryuin, whom she regards as her creator and mother, and she seeks to further the goals of the Revocs Corporation, driven by a desire for Ragyo’s approval.

Nui’s role in the narrative is that of a persistent, chaotic force that directly challenges Ryuko. She embodies the personal and emotional stakes of Ryuko’s revenge, as her cold revelation of murdering Isshin Matoi adds depth to the conflict. Throughout the series, Nui does not undergo traditional character growth or redemption; instead, she remains a consistent source of antagonism that forces Ryuko to grow and adapt.

Key relationships define her presence. With Ryuko Matoi, Nui maintains a complex dynamic of rivalry and twisted kinship, viewing Ryuko both as a sibling and an opponent. This connection shifts between playful mockery and intense combat. With Ragyo Kiryuin, Nui is fiercely loyal, seeing herself as a daughter carrying out her mother’s will. Her interactions with other characters often serve to catalyze their development, underlining her role as a formidable antagonist.

Nui wields a purple scissor blade that is the matching half of Ryuko’s red blade, and she is highly skilled in its use. Her body, composed of life fibers, grants her superhuman agility, speed, and resilience. She can manipulate these fibers to heal from severe injuries and even alter her appearance at will. Her signature technique, Shinra-Kōketsu, allows her to cut through almost any material, making her a nearly unstoppable combatant. Despite her overwhelming power, her overconfidence can create openings for determined and inventive opponents. These abilities, combined with her unsettling personality, make Nui Harime a memorable and integral antagonist in the story.