Placing Nezuko in a box he carries on his back, Tanjiro travels with her on a mission to a town northwest where young girls are vanishing at night. There he faces a demon, which has morphed into three separate entities and is capable of a "Blood Demon Art" - special spells that demons can use when they gain enough power. Tanjiro recalls Urokodaki informing him of blood demon art and the thousand-year-old progenitor of all demons, as well as the only one who can turn humans into demons: Muzan Kibutsuji.