A Forged Bond

The eighteenth installment of the Kimetsu no Yaiba anime closes the Mount Natagumo arc's opening clashes. Shinobu and Giyu reach the mountain and find scores of dead corpsmen. While Tanjiro and Inosuke struggle against the towering Father of the Spider Family, Zenitsu fights to slow the venom spreading through him atop the suspended dwelling. Thrown far from the battle, Tanjiro discovers the young demon Rui tormenting a girl he claims as kin, and the boy's furious response sets a new confrontation in motion.

The Father of the Spiders

Father emerges to crush the intruders, and Tanjiro's Water Wheel cannot pierce his armored arm. After pinning the demon under a felled tree, Tanjiro attempts the Tenth Form only to be blocked and flung away, leaving Inosuke alone with the monster. Inosuke severs Father's forearm, but the demon sheds its outer skin to reveal a stronger body.

Shinobu finds Zenitsu

As Zenitsu's limbs wither and his breathing falters, he clings to his late master's encouragement. Shinobu lands beside him and asks if he is unharmed.

A bond declared false

Tanjiro slows his own fall and follows a cry of pain to Rui, who is slashing Daughter's face. When Rui insists they share a family bond, Tanjiro counters that he smells only fear, hatred, and revulsion between them, calling the tie a fabrication and enraging the demon. Elsewhere, Giyu arrives in time to save the dying Inosuke, slicing Father apart with the Fourth Form.

The episode adapts manga chapters 35 through 37. The two eyecatchers reproduce the covers of chapters 36 and 37. The sequence of Shinobu and Giyu surveying the mountain does not appear in the source manga. In the printed version Tanjiro lands cleanly after using the Second Form, whereas the anime has his momentum slowed but still slams him into a tree.