"Twilight of the Cockroaches" is a 1987 anime film that blends live-action and animation to tell a unique and allegorical story. The narrative centers on a colony of anthropomorphic cockroaches living in the apartment of a human named Saito. The cockroaches, led by their leader, Napoleon, have established a symbiotic relationship with Saito, who tolerates their presence and provides them with food scraps. The cockroaches view Saito as a benevolent figure, unaware of the broader human world's hostility toward their kind.

The fragile balance is disrupted when Saito's girlfriend, Naomi, moves in. Unlike Saito, Naomi despises the cockroaches and begins a relentless campaign to exterminate them. This shift forces the cockroaches to confront the harsh realities of their existence. The story focuses on the struggles of the cockroach colony, particularly through the perspective of Hans, a young cockroach who becomes a key figure in their survival efforts. Hans forms a bond with a female cockroach named Ichiro, and their relationship becomes a central emotional thread as the colony faces increasing threats.

As the conflict escalates, the cockroaches are forced to adapt to new challenges, including the introduction of advanced extermination methods and the arrival of a rival cockroach colony. The narrative explores themes of survival, coexistence, and the often brutal dynamics between species. The film's unique blend of animation for the cockroaches and live-action for the human characters creates a striking visual contrast, emphasizing the divide between the two worlds.

The story culminates in a dramatic confrontation between the cockroaches and Naomi, leading to significant losses for the colony. The film ends on a somber yet reflective note, highlighting the resilience of the cockroaches and the cyclical nature of their struggle for survival. Through its allegorical approach, "Twilight of the Cockroaches" offers a thought-provoking exploration of power dynamics, environmental conflict, and the fragility of coexistence.