To Hell

Frail from birth, Rui could barely walk until Muzan turned him into a demon under the guise of saving him. He gained strength but lost the daylight and was driven to feed on human flesh. After his parents found him beside a victim, his father raised a blade to end his son's life while his mother wept. Rui, wounded and confused, struck them both down, dismissing their love as hollow.

His mother's dying apology and his father's willingness to share the burden of his sins only reach him too late. Muzan returns to whisper that the parents were to blame, and the grieving child clings to that lie despite knowing the fault is his own.

Rui's origin is revealed in full: his transformation by Muzan, the night he killed his parents, the lie that absolved him, and his doomed attempt to rebuild a family among other demons. As his burning body fails, Tanjiro senses the sorrow in him and lays a hand on him in comfort.

In death, Rui is reunited with his parents, who vow to follow him even into the afterlife, and he weeps as his human form returns. Giyu then confronts Tanjiro for his compassion, and Tanjiro insists that demons, once human, deserve pity even as he ends them. Giyu later blocks Shinobu's attempt to kill Nezuko.

This chapter completes the emotional arc of the Spider Family confrontation, framing Rui less as a villain than as a broken child manipulated by Muzan. Tanjiro's argument that demons are tragic, hollow figures rather than worthless monsters becomes a defining statement of his character.

The installment corresponds to Episode 21 and is collected in Volume 5.