Kimecu no jaiba

Become the blade that cuts down despair. 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 matters 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 fates of humans and demons intertwine...begins now! (Anime Ltd)