Demon Slayer is set within a very distinct time period in Japan's real-world history, something which is observable in the show's environments. One of the most distinctive elements of Demon Slayer's visual design is the era in which it is set, as this lends not only to the designs of the world the series takes place in, but also the characters themselves. However, the show's setting adds more to the story than a distinct aesthetic.
The series follows Tanjiro Kamado, a young man whose peaceful life is changed one fateful day when a demon attack results in the loss of his family. Only his younger sister Nezuko survives the encounter, but with the demon results in her becoming one as well, though she retains enough of her humanity to recognize her brother. With nowhere else to go, the mysteriously scarred Tanjiro Kamado seeks out the mysterious Demon Slayer Corps to find a remedy for his sister's condition and to the Corps in their mission to protect others from the demons that emerge at night.
The official synopsis for the series discloses that the plot takes place during Japan's Taisho period, which occurred in the early 20th century, and inspiration from this time is visible in some of the character designs and the environments. The specific decision to set Demon Slayer in the Taisho period is intriguing because of how it affects the story's more fantastical elements, such as the powers of the Demon Slayers and their seemingly magical swords. Throughout the show, there are significant cultural differences between rural Japan and the country's more modernized locations, as the early chapters of Tanjiro’s journey take him to villages where people believe in spirits enough that they stay indoors at night to stay safe from demons. When his travels take him beyond the countryside, Tanjiro finds a massive contrast between the countryside and the city, as he discovers when he travels to Tokyo that not only do its citizens use new inventions like electrically-powered lights and locomotive engines, but they walk the streets at night in large crowds, completely unaware of the supernatural beings in their midst. Essentially, Demon Slayer's setting is one in which most of the population has come to consider demons to be nothing more than myths.
The societal shifts of the Taisho period provide context for why most ordinary civilians seen in The demons which function as Demon Slayer's antagonists appear as though they have almost been forgotten by most of the population due to the changes that resulted during the Taisho period, which makes the creatures all the more alarming when they appear before ordinary people.
The series’ Taisho setting also helps to justify the protagonists’ unique character traits and backstories. In the same way that Demon Slayer associates cities with technological advancements, most locations set in the countryside are portrayed as having stronger ties to traditional beliefs, as seen with Tanjiro learning swordsmanship in an era when the practice appears to have become a thing of the past. In addition, Tanjiro’s two travel companions Inosuke and Zenitsu harken back to the idea of folklore through their backstories, with the pig head wearing Inosuke having been raised in the wilderness by boars, while Zenitsu survived being struck by lightning. Overall, Demon Slayer makes use of inspiration from the Taisho period in order to create a memorable world defined by its balance of modern and mystical elements.
