"Mendako no Menmen" is a surreal and darkly comedic anime series that explores themes of identity, societal expectations, and the absurdity of human behavior. The story centers on Menmen, a sentient octopus-like creature who inexplicably finds himself living in a human-dominated society. Despite his non-human appearance, Menmen strives to assimilate into everyday life, taking on mundane jobs and navigating the complexities of human relationships. His struggles are compounded by the constant prejudice and misunderstanding he faces due to his appearance, which often leads to bizarre and humorous situations.

The narrative unfolds in a series of episodic vignettes, each highlighting Menmen's attempts to fit into various societal roles, such as a salaryman, a teacher, and even a celebrity. These scenarios are often exaggerated and satirical, reflecting the absurdity of societal norms and the lengths to which individuals go to conform. Menmen's interactions with humans range from heartwarming to deeply unsettling, as he encounters both kindness and cruelty in equal measure. Key characters include his human coworker, Tanaka, who serves as a reluctant ally, and a mysterious figure known only as The Masked One, who seems to have a deeper understanding of Menmen's origins and purpose.

As the series progresses, subtle hints about Menmen's true nature and the world he inhabits are revealed. The line between reality and fantasy becomes increasingly blurred, with surreal dream sequences and symbolic imagery suggesting that Menmen's existence may be a metaphor for alienation and the search for self-acceptance. The tone of the series shifts between dark humor, poignant introspection, and moments of outright absurdity, creating a unique and thought-provoking viewing experience. The story concludes ambiguously, leaving Menmen's ultimate fate and the true nature of his world open to interpretation.