Dungeon Ant A is a large black Labyrinth Ant with distinctive green eyes, inhabiting the dungeon environments. This character serves Kinji Ninomiya and belongs to an ant colony ruled by an Ant Queen.

The colony expanded into the mining dungeons after the disappearance of the dragon Rim, who had previously preyed upon their workers. Following a transformative event where Kinji Ninomiya used a potion to communicate with the ants, he introduced concepts of workers' rights and unionization to the colony. This led Dungeon Ant A and other workers to demand better treatment from their queen.

The Ant Queen initially responded with hostility, preferring to replace dissenting workers rather than negotiate. The dynamic shifted with the return of Rim, whose presence and the queen's recognition of Kinji's influence led to a new alliance. As a result, Dungeon Ant A, the queen, and the entire colony became integral to Kinji Ninomiya's plan to take over the Raiza'ha Mining Corporation and establish his own enterprise.