Nyan recurs as a cat-like character engaged in intergalactic ventures. His background identifies him as a spacefaring feline merchant, frequently operating alongside the Cosmic Hunters; his precise origins are unspecified.

In Cosmic Fantasy 3, hostile cats attack his chicken-shaped spacecraft, causing a crash-landing on planet Aira. He subsequently encounters protagonist Rei, manipulating him into a quest to locate the seven rare Sebulrakis Stones scattered across Aira. Nyan employs opportunistic tactics, selling Rei essential items like a bridge for 1000 gold and tricking him into entering a royal marriage tournament under false pretenses. These actions drive Rei to recover one stone from a royal tomb, though Nyan's ultimate motives for gathering all seven remain undisclosed. The quest concludes with Nyan recruiting Rei for further off-planet adventures.

Nyan resurfaces during a time-travel crisis instigated by space pirates, interacting with younger versions of established characters; his specific role in resolving this event is not elaborated. His activities extend beyond the games: in the OVA *Galaxy Cougar's Trap*, he issues a distress signal while space pirates lure his allies into peril.

Throughout the series, Nyan maintains relationships with key figures like Yuu, Van, and Rei, alternating between comrade and manipulator. He exhibits traits of comedic relief and opportunism, frequently engaging in trade or deploying schemes that advance the plot. Physical descriptions are minimal beyond his feline appearance and occasional use of animal-themed spacecraft. His character persists across multiple installments, including Cosmic Fantasy 4, though his narrative contributions there are not detailed.