Aiko Zahn is a key figure within the Zahn Clan, the dominant force in the SAU underworld. As the younger brother of Rohm Zahn, his birthright positions him as a potential heir to the clan's leadership.

Frequent frustration with his older brother's short-sighted actions marks Aiko's relationship with Rohm, though he simultaneously recognizes Rohm's simpleness as a core strength. Despite their clashes, Aiko has never bested Rohm in physical combat.

Accompanying Rohm and Urdr-Hunt guide Bellows Xhosa to the Venus Sphere, Aiko bears one of the rings signifying participation in the Urdr-Hunt. During this event, the Zahn brothers focus on rival factions, particularly the Omden Colony Company. Observing Renzie Dablisco's confrontation with Wistario Afam, they devise a strategy to eliminate both competitors at once, aiming to thin the ranks of their competition within the hunt.

Aiko's role unfolds within the Urdr-Hunt narrative, which takes place chronologically between the two main seasons of the Mobile Suit Gundam IRON-BLOODED ORPHANS television series. This story was adapted into the special edition compilation Mobile Suit Gundam: Iron-Blooded Orphans – Urðr Hunt Special Edition: Path of the Little Challenger, which re-edits and expands the original Urdr-Hunt episodes.