Naki Kitō is the ruling matriarch of the Kito family, a secretive clan that has lived for centuries in a mountain village. She first appears as a short, stocky elderly woman with a large afro perm and a unibrow, often wearing a heavy bead necklace. This human appearance is a disguise; her true form is that of a subterranean being, a creature with two horns and a long, leech-like mouth, originating from the legendary underground city of Agartha. She has inhabited the surface world for over two hundred years, maintaining her cover by embodying the role of a tyrannical landlady who controls the land and its residents with an iron fist.

Her personality is defined by extreme arrogance, selfishness, and a ruthless sense of entitlement. She demands absolute obedience from anyone living on her property and is quick to use intimidation and violence to enforce her will. She is thick-skinned and unashamed, twisting her own self-interest into a supposed duty to protect the village. Her speech is coarse and masculine, and she commands her followers with an air of unchallenged authority.

Naki Kitō's primary motivation is the maintenance and expansion of the Kito family's sacrificial tradition. For generations, her family has offered human lives to a massive creature they call the Tsuchinoko, which is actually a Mongolian Death Worm, a giant carnivorous UMA that dwells beneath the volcano near their village. She claims these sacrifices are necessary to appease the worm and prevent a volcanic eruption. However, it is later revealed that she has spent two centuries deliberately feeding the worm in order to grow it to an enormous size, suggesting a larger, undisclosed ambition for its power.

In the story, she serves as a major antagonist during the Cursed House arc. She and her sons target Jin Enjoji (Jiji), his family, and his visiting friends Momo Ayase and Ken Takakura (Okarun) as potential sacrifices. When the main characters resist, Naki Kitō fights them with surprising physical prowess. Despite being in her human guise, she possesses superhuman strength, able to punch through walls and overpower Momo's psychic abilities. Her signature technique is the "Anakonda," a powerful double-handed thrust preceded by a strange chant referencing "Jenifa" and "Ropesu."

After the defeat of the Mongolian Death Worm, Naki Kitō reveals her true subterranean form and escapes. She later reappears later in the manga, having cultivated a new worm, and seeks revenge against Momo for destroying her centuries of work. This leads to a confrontation on an airplane, culminating in her being launched to the moon by the Evil Eye. Despite this, she survives and continues to nurse her grudge, remaining a persistent, antagonistic presence in the overarching narrative.

Her key relationships are defined by hierarchy and conflict. She rules over her sons, who address her as "Mother" and blindly obey her commands. She views Jiji, Momo, and Okarun as intruders and obstacles to be eliminated, developing a deep personal hatred for Momo after her plans are ruined. Naki Kitō's development is minimal in terms of redemption; she remains staunchly loyal to her twisted goals and only grows more vengeful after her defeats.

Notable abilities include her shape-shifting disguise, extreme longevity, superhuman strength and durability, and a keen understanding of the supernatural ecosystem she manipulates. She also appears to have some resistance or immunity to certain memory-wiping curses, retaining her awareness of Momo when others forget. Her combat style blends brute force with theatrical, unpredictable movements, making her a dangerous opponent even without her subterranean powers fully unleashed.