"Is It Wrong to Try to Pick Up Girls in a Dungeon? III" continues the adventures of Bell Cranel, a young adventurer in the city of Orario, where gods and mortals coexist. The third season focuses on the Xenos arc, introducing a new layer of complexity to the dungeon's ecosystem. The Xenos are sentient monsters capable of thought and emotion, challenging the traditional view of monsters as mindless enemies. Bell encounters a wounded Xenos named Wiene, forming an unlikely bond that puts him at odds with the rest of Orario's adventurers and gods.

As Bell protects Wiene and other Xenos, tensions rise between those who see the Xenos as a threat and those who believe in coexistence. The story explores themes of prejudice, morality, and the blurred lines between friend and foe. Key characters like Ais Wallenstein, Hestia, and Hermes play significant roles, with Ais grappling with her own past and Hermes manipulating events to test Bell's resolve. The narrative delves deeper into the dungeon's mysteries, revealing its connection to the Xenos and the gods' hidden agendas.

The season builds on the established world, expanding its lore while maintaining a focus on Bell's growth as a hero. His unwavering idealism and determination to protect the Xenos drive the plot, leading to intense battles and emotional confrontations. The story balances action, character development, and moral dilemmas, culminating in a climactic resolution that leaves lasting implications for Orario and its inhabitants.