Japan is presently in its Taisho Period. The family of Tanjiro, a kind-hearted youngster who sells charcoal for a living, is murdered by a demon. To make matters worse, his little sister Nezuko, the sole survivor, has been changed into a demon herself. Tanjiro resolves to become a "demon slayer" so he may transform his sister back into a human and defeat the demon that slaughtered his family.