Hans hails from a militaristic cockroach tribe waging relentless war against their human adversary Momoko within her apartment. Their conflict revolves around food raids and retaliatory insecticide assaults by Momoko.

Injured during combat with Momoko, he seeks sanctuary in the apartment of the pacifist Hosino tribe. His eyewitness descriptions of human extermination efforts clash with the Hosino’s complacency under their neglectful human, Saito. While recovering, he kindles a romance with Naomi—a Hosino member betrothed to Ichiro—fueling discord among the tribe.

After healing, he returns to Momoko’s apartment, trailed covertly by Naomi. They cohabitate for three weeks as she witnesses his tribe’s brutal struggle against human aggression. When Naomi departs, his tribe later advances on Hosino territory intending invasion. Discovering famine from human extermination, they instead ally with the Hosino to combat the shared human threat.

During the joint assault on Saito and Momoko, his leaders declare him a potential savior and command his retreat. Fleeing intensified insecticide deployment, he is crushed by a book dropped by Momoko. His legacy survives through Naomi’s pregnancy: her offspring display his physical traits alongside Ichiro’s, confirming his genetic role in birthing insecticide-resistant cockroaches.