This is the Taisho period in Japan. Tanjiro, a benevolent boy who sells charcoal for a living, finds his family slaughtered by a demon. To make matters worse, his younger sister Nezuko, the only survivor, was herself transformed into a demon. Although devastated by this grim reality, Tanjiro decides to become a "demon hunter" so that he can transform his sister into a human and kill the demon who slaughtered his family.