Eight episodes in now on Kimetsu no Yaiba and I find I like it more. It's basically a zombie/vampire show hybrid. In episode seven we meet Muzan Kibutsuji, the original demon, the only one able to turn people into demons, or so we're told at first. Tanjiro is trying to track him down in the hopes of finding a cure for his sister, Nezuko, who's been turned into a demon.
When Tanjiro does track down Muzan, it's in a crowded city street. Muzan is with his ordinary wife and child, apparently living amongst humans as one of them. As Tanjiro watches, he scratches the neck of a passer-by unobserved, immediately changing the man into a demon.
This man begins mindlessly attacking his wife, the sudden violence and disruption of normalcy resembling many zombie movies and shows. My read on zombies for years in Western fiction is that they are a manifestation of a suppressed fear of poverty and the poor. The poor have become some terrible, shadowy horde, defined mainly by their constant, persistent needs (I'm reminded of Sylvia Plath's "The Thin People"), like hunger, for the flesh of the "real", or people who can afford normal lives. Another part of the horror is that someone you know, who's wealthy and very like you in beliefs and lifestyle, may at any time become poor, and thus number among that frightening horde, one which grows as poverty increases in proportion to an increasingly exclusive wealthier class.
So it makes sense in Kimetsu no Yaiba for the leader of the demons to be a wealthy man converting people into mindless eaters of flesh (one could draw comparisons to David Cronenberg's Rabid). Except they aren't all mindless and Tanjiro isn't portrayed as perverted or misguided, like characters on The Walking Dead, for wanting to keep a particular demon alive. Though given the tendency for anime to indulge in stories of incest, that may change. But Nezuko is certainly not portrayed as wicked.
Like many beautiful girls in anime, she's portrayed as a kind of pet. Although other demons can talk, Nezuko is voiceless, forced to wear a bamboo gag to prevent her from biting Tanjiro. Why this is a continued necessity after Nezuko actively fights on Tanjiro's side is not explained. Really, it's just because it makes her so darn cute.
The show also doesn't waste opportunity to utilise the sexual appeal of traditional Japanese attire for women which did not include panties. Nezuko enjoys fighting with her legs and many shots imply her exposed crotch is tantalisingly just off screen.
Vampires are the usual symbol of a predatory wealthy class, something which has been deconstructed to no end, reaching a peak in Andy Warhol's Blood for Dracula (despite my dislike for deconstructionism I still find that movie really cute). But for this reason, it also makes a kind of sense for the talking demons in Kimetsu no Yaiba to be like vampires. One of them even expresses a justification for killing women in his opinion that if women are permitted to age they become unappealing. By devouring them at a younger and more beautiful age, he feels he's doing both them and society a favour. One might read this as the compulsion for cosmetic surgery among the wealthy also being a convenient class signifier but I think it fits more generally into the psychotic rationalisation invoked to dismiss the plight of the poor.
So the monsters on the show are symbols of both the rich and the poor--the show is making a broader commentary than one on simply economic status. It's a show about a changing culture. Tanjiro, like many heroes, comes from a small town where he and his family led a traditional, simple life. The attacks of a demon from the city forces Tanjiro to travel to the city, too, after taking up a new and strange career as a demon hunter. He's drawn in by the mechanisms of an emerging economic framework.
Unlike the simplistic socialist yearnings found in the fantasies of some of America's idle class, Kimetsu no Yaiba does not condemn an essentially capitalist society, only one based on the illusory system of a demon robbing ordinary citizens of their ordinary lives and minds. In Japan, where conformity to the system involves wearing appropriate clothes, using appropriate gestures, and framing all verbal exchanges in a particular context of civility and respect, becoming a demon, either mindless or deluded, holds another kind of terror. At the same time, it offers tantalising liberation.
Which is another way of reading Nezuko. Not being able to speak would seem to limit her means of expression but in a society where conversation is often an enforced means of supporting a communal etiquette imperative, being outside this conversation confers a kind of freedom. Similarly, Nezuko's fancy legwork in a fight may be tantalising to the viewer but it may also be liberating for her to move outside an ethic of modesty based on repression and restraint. Also, at the same time that Tanjiro's new career represents perversion and violence, it also confers on him extraordinary value and competence. After all, who wants to watch an anime about the boy leading the life of an ordinary basked weaver?
The series is set in the Taiso era, the early 20th century, when Japan was undergoing a transition from the feudal culture that had persisted for centuries into a modern industrialised nation. As people found themselves adjusting to new roles, economic status and social status transformed. Like many periods of such change, it must have been frightening. It makes sense for Kimetsu no Yaiba to show a concurrent demoniac transition.