Pretend Family

The twentieth episode reveals the truth behind Rui's imitation family. After Tanjiro believes he has won, the demon proves he severed his own head with his threads to escape death, then attacks again. Giyu arrives and ends Rui with ease using a previously unseen form. A long flashback shows how Rui assembled his false household by forcing demons into roles, and the present-day thread follows Daughter as she flees only to meet the Insect Hashira, Shinobu Kocho.

Rui's survival and defeat

Tanjiro smells no ash and realizes Rui lives. As the Lower Rank traps him in the Murderous Eye Basket, Giyu cuts the web apart and tells Tanjiro to rest. Rui hurls a spinning web of blood threads, but Giyu answers with the Eleventh Form, Dead Calm, halting the strike and decapitating the demon in an instant.

The false household

Daughter recalls Rui rescuing her from slayers and forcing his blood upon her, reshaping her body. She learns the members share no real ties and that any who defy Rui face brutal punishment. An older sister who plots escape is left strung up to burn in the sun.

Shinobu versus Daughter

Daughter cocoons the slayer Murata in dissolving silk, but Shinobu pins her and questions her about her victims. Refusing the demon's pleas, Shinobu strikes with Insect Breathing, Butterfly Dance: Caprice. Her blade cannot behead, yet her wisteria poison kills Daughter regardless, and she frees Murata.

The episode covers chapters 41 and 42, and the second eyecatcher recreates the title page of Volume 5. Onscreen Rui's clash with Giyu comes before the Shinobu fight, which the manga reverses. The adaptation expands the Spider Family's backstory and adds one of Daughter's memories absent from print. In the manga Shinobu interrogates Daughter while she stands, but the anime pins her down.