Spider Family

Rui's false family of demons on Mount Natagumo: Mother, Father, Elder Brother and Elder Sister.

The Spider Family is the group of demons that Rui forces into the roles of a family. Its "Mother", a young girl turned into a demon whose appearance Rui altered, controls her victims like puppets with silk threads attached by small white spiders, and her strongest weapon is a headless demon corpse with scythe-like arms.

Quick Facts

Leader

Rui

Members

Mother
Father
Elder Brother
Elder Sister

Mother's weapon

Headless demon corpse with scythe-like arms

Slain by

Tanjiro
Giyu
Zenitsu
Shinobu

Facts from the source article.

Background

Living in great fear of Rui, the Mother ultimately allows Tanjiro to slay her when they fight, which sets her free. The "Father" is the least human of the family, a spider's head atop a giant humanoid body; he attacks Tanjiro and Inosuke until Giyu intervenes and kills him.

The "Elder Brother", one of the two members who does not look human, has a human head on a spider's body and can turn humans into monstrous semi-spiders when his minions bite them; Zenitsu kills him. The "Elder Sister" took her role after begging Rui for safety from the Demon Slayers; she spins acidic cocoons of thread that dissolve her victims into food, and nearly kills Murata before Shinobu subdues and kills her.