"Peddler in Another World" centers on Shiro Amata, a modern-day salesman who finds himself transported to a fantasy realm after a mysterious encounter. In this new world, magic, monsters, and medieval-like societies coexist. Shiro’s unique advantage lies not in combat prowess or magical ability but in his sharp business acumen and knowledge of modern marketing strategies. Equipped with a smartphone that inexplicably functions in this world, he uses it to analyze market trends, track inventory, and communicate with potential clients.

The narrative explores Shiro’s journey as he establishes himself as a merchant in a world unfamiliar with modern commerce. He begins by selling everyday items from his world, such as soap and umbrellas, which are perceived as exotic and valuable in the fantasy setting. His innovative approach to trade earns him both allies and rivals, including nobles, adventurers, and other merchants. Shiro’s interactions with these characters reveal the complexities of the world’s economy and politics, as well as the cultural differences between his modern perspective and the medieval mindset of the inhabitants.

Key characters include Rize, a skilled blacksmith who becomes Shiro’s business partner, and Milka, a young girl with a mysterious connection to magic who assists him in his ventures. The story also introduces antagonists such as rival merchants and corrupt officials who seek to undermine Shiro’s success. As Shiro’s influence grows, he becomes entangled in larger conflicts, including power struggles between factions and the looming threat of a demonic invasion.

The manga balances its focus on commerce with elements of adventure and world-building. Shiro’s journey is not just about accumulating wealth but also about understanding the intricacies of the new world and forming meaningful relationships with its inhabitants. The narrative highlights themes of resourcefulness, cultural exchange, and the impact of modern ideas on traditional societies. Through Shiro’s experiences, the series provides a detailed exploration of trade, innovation, and the challenges of adapting to an unfamiliar environment.