"Penguin Highway" is a science fiction anime film based on the novel by Tomihiko Morimi. The story centers on Aoyama, a highly intelligent and curious fourth-grader with a penchant for scientific inquiry. One day, penguins inexplicably appear in his quiet suburban town, far from any ocean. Intrigued by this phenomenon, Aoyama begins investigating the cause, documenting his observations in a meticulous notebook. His curiosity leads him to a mysterious woman who works at a local dental clinic, known simply as "The Lady." Aoyama develops a deep admiration for her, and she becomes a key figure in his investigation.

As Aoyama and his friends, including his classmate Hamamoto, delve deeper into the mystery, they discover that the penguins are connected to strange, otherworldly occurrences in the town. These include the appearance of floating orbs of water and a bizarre, expanding area known as "The Sea," which defies the laws of physics. The Lady reveals that she has a unique connection to these phenomena, though the exact nature of her role remains enigmatic. Aoyama's scientific approach and determination drive the narrative as he seeks to unravel the truth behind the penguins and the surreal events unfolding around him.

The story explores themes of curiosity, the boundaries of human understanding, and the transition from childhood to adolescence. Aoyama's relationships with his friends and The Lady are central to the narrative, highlighting the interplay between logic and emotion. The film builds toward a climactic revelation about the origins of the penguins and The Sea, tying together the scientific and fantastical elements of the plot. Through its blend of mystery, science fiction, and coming-of-age themes, "Penguin Highway" presents a thought-provoking and imaginative tale.