"All Purpose Cultural Cat Girl Nuku Nuku" centers around Ryunosuke Natsume, a young boy whose life takes a dramatic turn when his father, Kyusaku Natsume, a brilliant but eccentric scientist, installs the brain of a stray cat into an advanced android body. This android, named Nuku Nuku, is designed to protect Ryunosuke and serve as a surrogate mother figure after his parents' separation. Nuku Nuku's feline instincts and superhuman abilities often lead to chaotic and humorous situations, blending action with comedy.

The series explores the dynamic between Ryunosuke, Nuku Nuku, and his mother, Akiko Natsume, who is the CEO of Mishima Heavy Industries. Akiko is determined to reclaim Nuku Nuku, viewing the android as corporate property and a potential weapon. This conflict drives much of the plot, as Akiko deploys various advanced technologies and agents to capture Nuku Nuku, while Ryunosuke and his father strive to keep her safe. Nuku Nuku herself is a central figure, embodying both the innocence of a cat and the strength of a high-tech machine, often resolving conflicts with a mix of brute force and childlike charm.

The narrative is episodic, with each installment presenting a new challenge or threat, often involving Akiko's relentless pursuit or other external forces. Despite the frequent action sequences, the series maintains a lighthearted tone, emphasizing the comedic aspects of Nuku Nuku's dual nature and her interactions with the human characters. Themes of family, loyalty, and the ethical implications of advanced technology are subtly woven into the story, providing depth beneath the surface of its comedic and action-oriented exterior. The characters are distinct, with Ryunosuke serving as the emotional anchor, Kyusaku as the quirky inventor, Akiko as the determined antagonist, and Nuku Nuku as the heart of the series, balancing humor and heroism.