Normally, she looks just like a human, but when she sees mice—including Mouse-Man—or fish, or gets angry and excited, her eyes turn golden, her ears split open, and she reveals sharp fangs, transforming into a monstrous cat. She absolutely loves fish, dried bonito flakes, and mice. Like Kitaro, Old Man Eyeball, and Mouse-Man, she is a character created by Shigeru Mizuki, yet she is also recognized as a yokai. She harbors a shy, unrequited love for Kitaro. Starting with the fifth anime series, she acquired the nickname “Nyanyanya the Catgirl” in contrast to “Gegege no Kitaro” and “Bibibi no Mouse-Man.” Her first-person pronouns vary depending on the work—“I” in the original manga and in the first, fifth, and sixth series; “atashi” in the third and fourth series, occasionally in the second, fifth, and sixth; and “atai” in the early original manga, the second series, and the “Ibun Yokai Kidan,” sometimes even in the third series—and they can also change according to her mood at the time.
Her origins lie in being a half-yokai born between a human and a yokai. Officially described in books supervised by Mizuki Pro as “a half-yokai just like Mouse-Man,” she rarely has scenes in the main story that explicitly acknowledge this background, unlike Mouse-Man.
In the early days of the original manga, several cat-girl-type yokai and cat-woman–like yokai appeared as Mouse-Man’s arch-enemies, but most were one-off guest characters. The first appearance of a cat-girl with a bob haircut and a one-piece dress as Kitaro’s friend was in the first series of the Weekly Shonen Magazine edition, in the story “Cat-Girl and Mouse-Man.”
It wasn’t until the Weekly Shonen Sunday edition that a cat-girl became a regular character in the role of Kitaro’s girlfriend. At that time, she sported a messy, tousled hairstyle and wore traditional Japanese clothing, looking quite different from the cat-girl in the Magazine version, and went by the name “Nekoko.” However, even then, design elements such as slanted eyes and round cheeks had already been established. This Nekoko was depicted as a human afflicted with a strange illness that turned her into a monstrous cat whenever she saw mice or fish, though she was explained not to be a yokai. Still, she herself referred to herself as “a kind of yokai” or “not interested in humans,” leaving her status ambiguous—whether she was purely a yokai or a human (she was never classified as a “half-yokai” like the cat-girl or Mouse-Man).
In the anime adaptations, she made her debut as a guest character in episode 20 of the first series, “Cat-Girl and Mouse-Man,” and appeared from the very first episode of the second series, becoming a regular member.[4] Key traits such as a red‑based outfit adorned with ribbons and expressions of romantic feelings toward Kitaro were firmly established during this period.
The cat-girl with the large ribbon, similar to the anime version, first appeared in the original manga and gained lasting popularity around the time of the third anime series in the 1980s—making her something of an imported character from the anime. It was then that her physical proportions were officially defined, a detail later published in various Kitaro encyclopedias issued by Kodansha and other publishers.
The cat-girl featured in “Kaiiki Nekomusume,” published under the pseudonym “Toji Shinichiro” by Mizuki in June 1958, who involuntarily transforms into a cat-faced creature upon catching the scent of Pacific saury, is considered the precursor to the cat-girls appearing in later Kitaro series. (At that time, this cat-girl went by the name Midori; her origin was tied to her father killing a giant black cat, after which she inherited cat-like traits due to the curse. Her birth was similarly portrayed as emerging from her mother’s grave, much like Kitaro’s own backstory.)
As for her attire, both in the original manga and the anime, her basic look consists of a white blouse paired with a red-to-pink suspender skirt. However, only in the second series does she wear a red one-piece dress with a white collar and large yellow polka dots. In Part One of “Gegege no Kitaro: Yokai Sen Monogatari,” she donned a jet-black gothic‑style gown, her hair styled as semi‑long shoulder-length locks. From Part Two onward, she adopted a short haircut similar to that of the fifth anime series.