Infiltrating the Entertainment District

The thirty-fifth anime episode, the ninth of season two, sends Tanjiro, Nezuko, Zenitsu, and Inosuke to the Entertainment District alongside the Sound Hashira. Tengen's three wives had been working undercover to investigate a demon, but he has lost contact with all of them. To learn what happened, the boys go in disguised and embed themselves in the houses where the women were stationed.

Unfamiliar with a red-light district, Tanjiro and Inosuke bewilder Zenitsu while Tengen loudly proclaims himself a god of flashiness and festivals. After a chaotic arrival in Yoshiwara, Tengen explains that the district only comes alive at night, making it ideal cover for a demon, and that his wives, Suma, Makio, and Hinatsuru, had each been placed in a separate house.

To slip the boys inside, Tengen presents them in clumsy makeup so that each house will take one in. Tanjiro, under the name Sumiko, joins the Tokito House. Inosuke, called Inoko, is taken by the Ogimoto House, where his hidden face surprises everyone. Zenitsu, named Zenko, is placed in the Kyogoku House and channels his fury at Tengen into a striking shamisen performance, vowing to rise to the top of the district.

While doing chores at the Tokito House, Tanjiro overhears talk that the madam who ran the Kyogoku House has recently died, along with mention of an oiran named Suma who supposedly fled her debts, recognizing the name as one of Tengen's wives. He awkwardly questions the oiran Koinatsu, who doubts Suma left of her own accord. Patrolling the rooftops, Tengen senses the demon is likely an Upper Rank. Meanwhile Inosuke overhears that Makio, another of the wives, refuses to leave her room. Behind a closed door, a demon is shown holding a bound woman captive and addressing her as Makio.

The anime adds an original sequence covering how the group first reaches the district, in which Inosuke keeps bolting off in excitement and a flustered Zenitsu wanders toward a group of workers before Tengen drags him back. The episode otherwise tracks the opening of the infiltration closely, establishing the three houses, the cover identities, and the first hints that an Upper Rank is concealed somewhere inside.