It is the Taisho Period in Japan.

Tanjiro, a kindhearted boy who sells charcoal for a living,

finds his family slaughtered by a demon.

To make matter worse, his younger sister Nezuko, the sole survivor,

has been transformed into a demon herself.

Though devastated by this grim reality,

Tanjiro resolves to become a "demon slayer"

so that he can turn his sister back into a human,

and kill the demon that massacred his family.

A sorrowful tale of siblings in which the faces of humans

and demons intertwine...begins now!

​

Source: Demon Slayer Kimetsu No Yaiba Anime Official USA Website (https://demonslayer-anime.com/)