"All Purpose Cultural Cat Girl Nuku Nuku" centers around a unique blend of science fiction, comedy, and family dynamics. The story revolves around Nuku Nuku, a cyborg created by the brilliant but eccentric scientist Ryunosuke Natsume. Nuku Nuku's body is constructed from advanced technology, but her brain originates from a stray cat. This fusion of feline instincts and human-like intelligence results in a character who is both endearing and unpredictable.

The narrative begins when Ryunosuke's estranged wife, Kyoko, kidnaps their son, Arisa, in an attempt to force Ryunosuke to return to her wealthy family's corporation, Mishima Heavy Industries. To protect Arisa, Ryunosuke installs Nuku Nuku as his son's bodyguard. Nuku Nuku's primary directive is to ensure Arisa's safety, but her cat-like behavior often leads to humorous and chaotic situations. Despite her advanced combat capabilities, Nuku Nuku's childlike curiosity and playful nature frequently complicate her missions.

Kyoko, determined to reclaim her family, deploys various advanced robots and gadgets to capture Arisa, leading to a series of confrontations with Nuku Nuku. These battles are interspersed with moments of domestic life, as Nuku Nuku adapts to living with Ryunosuke and Arisa. Her attempts to understand human emotions and relationships add depth to her character, while her interactions with Arisa highlight themes of family and loyalty.

The series balances action-packed sequences with lighthearted comedy, often deriving humor from Nuku Nuku's feline quirks and her misunderstandings of human behavior. The dynamic between Nuku Nuku, Ryunosuke, and Arisa forms the emotional core of the story, emphasizing the importance of unconventional family bonds. The narrative explores themes of identity, technology, and the blending of human and animal traits, all while maintaining a playful and engaging tone.