The King of Demons

Muzan recalls a life shadowed by death, beginning with his own near-stillbirth. Reflecting on Kagaya Ubuyashiki's words, he concedes that only feelings endure, yet insists his own will lives on too. Reaching toward Tanjiro, he transfers all of his blood into the boy, declaring that if Tanjiro survives he will become the strongest demon ever, and charging him to destroy the Demon Slayer Corps.

As Giyu kneels beside him, the tumor on Tanjiro's head vanishes and his eyes open with a demonic glare. He regenerates a lost arm and lashes out at a nearby Kakushi, whom Giyu shoves clear. Tanjiro's Demon Slayer Mark spreads across his face, echoing Kokushibo, and he revels in his new fangs and claws.

When the sun blazes overhead, Tanjiro begins to burn, but he soon adapts and shrugs off the light entirely, leaving the slayers stunned. Giyu warns everyone that Tanjiro has become a demon who must be restrained and exposed to the sun. Inosuke intercepts an attack on the wounded Giyu and, recalling the comradeship they share, finds himself unable to bring his blade down on his friend.

Pouring every drop of his own blood into Tanjiro, Muzan converts the boy into a demon.

Tanjiro develops immunity to sunlight, becoming a new demon king.

Giyu and Inosuke try to subdue him, but Inosuke cannot bring himself to strike.

Collected in Volume 23 as part of the Sunrise Countdown Arc, this chapter delivers one of the series' major twists by transforming the protagonist into the very enemy his comrades have spent years fighting. It begins the short conflict known as Demon Slayers vs Tanjiro Kamado.