Demon Slayer: Kimetsu no Yaiba

Since ancient times, rumors have abounded of man-eating demons lurking in the woods. Because of this, the local townsfolk never venture outside at night. Legend has it that a demon slayer also roams the night, hunting down these bloodthirsty demons. For young Tanjiro, these rumors will soon to become his harsh reality. Ever since the death of his father, Tanjiro has taken it upon himself to support his family. Although their lives may be hardened by tragedy, they've found happiness. But that ephemeral warmth is shattered one day when Tanjiro finds his family slaughtered and the lone survivor, his sister Nezuko, turned into a demon. To his surprise, however, Nezuko still shows signs of human emotion and thought. Thus begins Tanjiro's request to fight demons and turn his sister human again. <em class=de-emphasized>(from manga)</em>

Synopsis from Anime News Network