鬼に変貌してしまった妹を人間に戻し、家族を殺した鬼を討つため、心優しき少年・炭治郎は、"鬼狩り"の道を進む決意をする。
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.