Kikuri is a central figure in the storyline of Hell Girl: Fourth Twilight, where she continues to serve as a complex companion to Ai Enma. Her origins are shrouded in mystery, as no specific history or details of an early life are provided, but it is made clear that she is not human in her current state. She is identified as a youkai, the spirit of a young girl who appears to be around seven years old, with a distinctive appearance that includes unusually large, bright eyes featuring three white orbs or reflections. Technically, Kikuri functions as a vessel for the Master of Hell, though she appears to be largely unaware of this possession, which can manifest through her at critical moments.

Kikuri's personality is a striking blend of childish petulance and unsettling cruelty. Her usual demeanor is that of a badly behaved and demanding child who acts on impulse without logic or regret. She takes great delight in annoying those around her, particularly Ai's first three companions, whom she addresses with rude nicknames such as calling Wanyuudou "baldy," Hone Onna "old woman," and Ichimokuren "eyeball". Her amusement extends to acts of low-level destructiveness, like snipping flowers, and she has been shown giggling at a dying man or teasing individuals in pitiable conditions, demonstrating a twisted sense of humor and judgment. Despite these negative traits, Kikuri also possesses a more innocent and playful side. She enjoys exploring the human world, which is unfamiliar to her, and seeks out playmates, such as when she asked Takuma and Tsugumi to play with her. She has expressed a strong fondness for certain foods, like wieners, and openly states her liking for Ai, even shedding tears when Ai died.

Kikuri's primary motivation seems to be a desire to act on her own whims, enjoying the freedom to interfere with Ai's duties and explore as she pleases. She has also expressed a powerful and persistent desire to become the Hell Girl herself, becoming annoyed by anything that prevents her from achieving this goal. Her role in the story is that of a mysterious figure who is liminal between worlds, serving as both a companion to Ai and a wildcard element whose actions can have significant consequences. She is able to travel freely between the normal world and the Realm of Eternal Twilight where Ai resides, and she is also capable of bringing others into this realm.

Kikuri's key relationships are defined by her interactions with Ai and her other companions. She refuses to listen to almost anyone, with the sole exception of Ai, whose commands she obeys immediately and to a great extent. For instance, she would only leave a place when reminded that her actions would displease Ai, though she would still spitefully kick Ren as she left. While Ai seems to like her, the first three companions generally dislike Kikuri due to her behavior, though they retain a small degree of care for her, as shown when Wanyuudou once beat up two men to protect her. Her relationship with Yamawaro, introduced in the third season, is notably different; she is nicer to him, caring for his health and even threatening to send people who harm him to hell. However, she still treats him as a servant, requiring him to wind the key on her back to keep her mobile and demanding that he call her "Princess Kikuri". In the fourth season, Fourth Twilight, this dynamic continues, and she displays jealousy when Yamawaro pays attention to the new character, Michiru.

Kikuri undergoes notable development across the series. In the second season, Two Mirrors, she acts as a host for the Master of Hell, with its influence perhaps explaining some of her more negative actions. By the third season, Three Vessels, she has lost her original body and now inhabits a wind-up doll to be physically present in the human world. In this form, she requires the key on her back to be periodically wound to maintain movement, though she can still speak even when motionless. By the time of Fourth Twilight, she has become a familiar part of Ai's entourage, with her identity as a doll-like figure and her role as a mischievous observer fully established.

Kikuri possesses several notable abilities. She can travel between dimensions, easily moving between the human world and the Realm of Eternal Twilight. She has demonstrated teleportation, capable of appearing and disappearing at will. Her abilities also include telekinesis, which she often channels through her loincloth to bind, suspend, or manipulate objects with precision. She has shown the power of hypnotism, using it to make a woman believe Kikuri was her daughter. Furthermore, she possesses the rare ability to revive people from comas and heal them, adding a layer of life manipulation to her supernatural skills.