Twilight of the Cockroaches

The Hosino Tribe lives in a city apartment owned by Mr. Saito and had waged war with humans in the past. The conflict ends when the human Hosino clan leaves and Saito arrives, with Sage acting as the negotiator who proclaims peace. The roaches remember this as Armistice Day and live in relative luxury while neglecting their traditional vigilance.

Ichiro and Naomi, two cockroaches in the Hosino tribe, are engaged and planning their wedding. Naomi harbors doubts about the relationship while Ichiro remains unable to fly. Their romance is nurtured under Sage's advisory presence.

A roach from another far-off tribe named Hans arrives at the apartment injured from a battle. Naomi finds herself drawn to him, developing feelings despite the ongoing tensions. Ichiro remains unaware of her growing attachment.

Naomi secretly follows Hans to an apartment owned by a woman named Momoko. Momoko initially tries to stomp on Naomi, and it is revealed that Hans' militaristic tribe is at war with Momoko's tribe, with both sides using tactics including insecticides.

Naomi and Hans stay together in the same apartment complex for three weeks, during which Naomi's loyalty to her original tribe wavers. They forge a fragile bond and keep their relationship largely secret from their tribes.

Across the complex, Saito and Momoko notice each other and begin seeing one another. The Hosino roaches are unaware of this budding connection, which complicates the social dynamics of the roach-human war.

During a visit, Naomi inadvertently returns to Saito's apartment and hides in Momoko's purse after a horrific experience in a roach motel. Ichiro remains oblivious to this sequence of events.

Ichiro and Naomi are reunited and decide to proceed with their wedding. Naomi claims to have amnesia and does not recall some of her time away. The couple presses ahead with the ceremony.

Momoko interrupts the wedding by launching a violent assault that kills many guests. Naomi, Ichiro, and the rest of the roaches escape the chaotic scene. The attack reveals how fragile peace has become.

During the funeral, Sage promises to discuss the attack with Saito. The next day, Sage is found dead, pinned to a dartboard, suggesting foul play. Meanwhile, Momoko and Saito intensify their extermination of the roaches.

Ichiro learns from elderly roaches that Sage fabricated the war and that Saito tolerated the roaches for reasons tied to his heartbreak. The elderly also reveal they had hidden during the war and never met Saito, casting doubt on the official history.

The elderly roaches teach younger generations how to forage and steal dropped food, but the roaches still grow hungry as the peace proves unsustainable. The sense of scarcity drives tensions within the roach community.

Hans's tribe arrives to invade, but upon learning the Hosino have little food, they propose an alliance to help drive humans out. Ichiro and Hans agree to settle their differences after the impending battle. The uneasy alliance reshapes who is fighting whom.

The allied roaches confront the humans in a major confrontation. As the fighting escalates, Hans is killed when a book falls on him during the escape orchestrated by Momoko. The roaches push forward, but the loss is devastating.

Naomi survives a lethal insecticide strike after having visions from her late grandmother that she is immune, a trait she will pass to her offspring. She escapes with Ichiro's help to a shrine-like toy in the yard, planning a new life away from humans. The epilogue shows Naomi with a large litter of immune children, some resembling Ichiro and Hans.