Demon Slayer: Muzan's Younger Brother from the Start, Two Demon Kings Face Off

Muzan Kibutsuji's younger twin brother, Yosuke Ubuyashiki, transmigrates into this world, only to find himself in a body so frail that even breathing is a struggle. As the brothers both hover on the brink of death, the same doctor saves their lives with an experimental drug. When Yosuke wakes, a System notification sounds: he has been transformed into an Origin Demon.

Yosuke gains Blood Demon Art and the body of a Demon King, while his older brother, Ubuyashiki Maiy, completely abandons his humanity, takes the name Muzan Kibutsuji, and becomes the progenitor of demons. At their first face-to-face encounter, Yosuke's arm is torn off with ease. The gap in their power is like a chasm.

With her dying breath, their mother entrusts him with the responsibility of cutting off the source of the calamity. From then on, Yosuke sets out to hunt demons. Over the long years, he meets Tamayo and lives to see the birth of Yoriichi Tsugikuni. The Demon Slayer Corps rises, Sun Breathing enters the world, and at last the blades that will slay demons take shape.

But Muzan is also secretly gathering strength and creating the Twelve Kizuki. The two forces are bound to clash. Yosuke must become strong enough before the decisive battle, because in the end, he must personally kill the brother who plunged the world into hell.

This novel and its characters are entirely fictional. Any resemblance to real people or events is purely coincidental. Do not imitate.