Following the tragic events of the Mugen Train arc, Tanjiro Kamado, Zenitsu Agatsuma, and Inosuke Hashibira join forces with the Sound Hashira, Tengen Uzui, on a covert mission to the Yoshiwara Entertainment District. Their objective is to locate Tengen's three missing kunoichi wives, who were investigating rumors of demonic influence in the dazzling yet treacherous district. As the group goes undercover to sniff out the threat, they soon discover that the district is infested by Daki, an Upper Rank Six demon masquerading as a high-ranking courtesan. The ensuing battle pushes Tanjiro and his comrades past their absolute limits, forcing them to awaken new powers and fight side-by-side with a Hashira against one of Muzan Kibutsuji's most powerful and lethal subordinates.