"Penguin Highway" is a science fiction manga adaptation of Tomihiko Morimi’s novel, illustrated by Keito Yano. The story centers on Aoyama, a highly intelligent and curious fourth-grade boy who approaches life with a methodical and scientific mindset. Aoyama’s routine is disrupted when penguins mysteriously appear in his landlocked town, far from any ocean. Intrigued by this phenomenon, he begins investigating their origin, documenting his findings in a notebook.

Aoyama’s investigation leads him to a local dental assistant, known as "Onee-san," whom he admires deeply. Onee-san possesses a mysterious connection to the penguins, as they seem to manifest around her. As Aoyama delves deeper, he discovers that the penguins are linked to a strange, otherworldly sphere that appears in a nearby forest. This sphere, referred to as the "Sea," exhibits bizarre properties, defying the laws of physics and seemingly connected to a parallel world.

The narrative explores Aoyama’s interactions with his classmates, including his friend Hamamoto, who shares his curiosity and assists in unraveling the mystery. Together, they uncover the connection between Onee-san, the penguins, and the Sea, revealing a complex interplay of time, space, and memory. The story blends elements of surrealism and coming-of-age themes, as Aoyama grapples with the boundaries of his understanding and the emotional complexities of growing up.

The manga maintains a focus on Aoyama’s perspective, emphasizing his analytical approach to the inexplicable events around him. The penguins serve as both a literal and symbolic presence, representing the intersection of the ordinary and the extraordinary. As the mystery deepens, the narrative builds toward a poignant exploration of curiosity, human connection, and the limits of knowledge, culminating in a resolution that ties together the fantastical elements with Aoyama’s personal growth.