After the harrowing events aboard the Mugen Train, Tanjiro Kamado, his demon‑sister Nezuko, and friends Zenitsu and Inosuke join the flamboyant Sound Hashira, Tengen Uzui, on a dangerous undercover mission in the red‑light district of Yoshiwara. There, Tengen’s three kunoichi wives have gone missing while investigating rumors of a demonic presence. The team enters the district in disguise and soon confronts the fearsome Upper Rank demons Daki and Gyutaro. As long‑buried tragedies unfold, Tanjiro must unlock new strength and resolve in a battle that will test both heart and blade.