Union Arena One Punch Man launched during a period of expanding Japanese trading card game popularity in the West. The set brought Bandai's accessible collectible card game format to fans of the popular manga and anime series, capturing the character-driven appeal that made One Punch Man a cultural phenomenon. Union Arena's straightforward gameplay and manga-licensed properties positioned it as an entry point for collectors exploring TCGs beyond traditional trading card games. Saitama, the protagonist, appears here as a Super Rare card that represents the series' central figure—the overwhelmingly powerful hero stripped of his excitement by invincibility. Collectors seek cards of main characters like Saitama across licensed sets, valuing them as cornerstones of character collections and recognizing their cultural significance to fans of the franchise.