Twilight of the Cockroaches(1987)

Overview:

The cockroaches of Saito's apartment live in peace with their human host, who gives them lots of space to breed and plenty of leftovers to munch on. In the midst of these high living times, Naomi and Ichiro plan to get married and start a family. But when a hard-bitten stranger roach named Hans appears with news of war with the humans across the lawn, it foretells disruption-not only of Naomi and Ichiro's relationship, but of the hive's entire way of life.