Mount Natagumo Arc

The Mount Natagumo Arc is the fifth main storyline of the Kimetsu no Yaiba manga, spanning Chapter 28 to Chapter 44 and adapted across Episodes 15 through 21 of the first anime season. It is set on Mount Natagumo and follows the Tsuzumi Mansion Arc before leading into the Rehabilitation Training Arc.

The arc centers on a so-called family of spider demons who have claimed the mountain, with the child-shaped demon Rui sitting at the head of the household. It is one of the series' most pivotal early conflicts, raising the danger to a level that forces stronger members of the Corps to step in.

On Mount Natagumo, Tanjiro and his two companions, Zenitsu and Inosuke, run into a deadly group of demons bound together as a twisted family. The enemies are far above the trio's usual opponents, and surviving them demands every scrap of technique and good fortune Tanjiro can manage.

The crisis sharpens when Nezuko is seized and trapped in the spiders' webbing, turning the assault into a desperate rescue. As the fighting escalates, additional members of the Demon Slayer Corps arrive on the mountain to help purge the nest, but the cost is steep and several do not leave whole, or alive.

The confrontation builds toward Rui, the lower-rank demon directing the family. The clash with him pushes Tanjiro past his previous limits and showcases techniques that hint at the deeper lineage of his Breathing style, a thread the series develops in later arcs.

The mountain's spider clan is broken by the combined effort, but the battle exacts a heavy toll on the slayers who responded. The arc also marks the first real appearance of Hashira-level figures responding to a major threat, widening the scope of the Corps beyond Tanjiro's small group.

In the wake of the fighting, Tanjiro's unusual situation, a slayer protecting a demon, becomes impossible to ignore, setting up the reckoning with the Corps' leadership that follows in the next arc.