"Shibuya Goldfish" is a horror manga series written and illustrated by Aoi Hiroumi. The story is set in Shibuya, Tokyo, where a sudden and catastrophic event unfolds as giant, man-eating goldfish begin to invade the city. These monstrous creatures, resembling oversized goldfish with razor-sharp teeth, emerge from the sky and quickly overrun the streets, devouring anyone in their path. The narrative centers on a group of survivors who must navigate the chaos and find a way to escape the city while uncovering the mystery behind the goldfish invasion.

The protagonist, Hajime Tsukiyoda, is a high school student who becomes one of the few survivors after the initial attack. Hajime is resourceful and determined, but he is also deeply affected by the trauma of witnessing the carnage around him. Alongside him is Kaede Akikawa, a classmate who initially appears aloof but proves to be a capable and resilient companion. The two form a tentative alliance as they struggle to survive, encountering other survivors along the way, each with their own motivations and secrets.

As the story progresses, the survivors discover that the goldfish are not merely mindless predators but are part of a larger, more sinister phenomenon. The creatures exhibit strange behaviors, such as mimicking human voices and displaying an eerie intelligence. The group learns that the goldfish are connected to a mysterious entity known as the "Goldfish King," a colossal being that appears to control the swarm. The survivors must confront not only the physical threat of the goldfish but also the psychological toll of their situation, as paranoia and mistrust begin to fracture their fragile unity.

The manga explores themes of survival, human nature, and the fragility of societal structures in the face of an overwhelming threat. The characters are forced to make difficult moral choices, often blurring the line between self-preservation and altruism. The narrative is punctuated by intense action sequences and moments of suspense, as the survivors face increasingly dire situations, including encounters with mutated goldfish and otherworldly phenomena.

As the group delves deeper into the mystery, they uncover clues suggesting that the goldfish invasion may be tied to a larger conspiracy involving scientific experimentation and the manipulation of reality. The story builds toward a climactic confrontation with the Goldfish King, raising questions about the nature of the creatures and the possibility of stopping the invasion. Throughout the series, the tension between hope and despair is a recurring motif, as the characters grapple with the uncertainty of their survival and the broader implications of the catastrophe.