Why did Muzan spare Nezuko?

Why Did Muzan Spare Nezuko?

It’s one of the lingering questions in Kimetsu no Yaiba: Why did Muzan Kibutsuji, the ruthless progenitor of all demons, choose to spare Nezuko Kamado instead of destroying her alongside her family? After all, Muzan has never shown mercy—his nature is defined by cruelty and survival. Yet, Nezuko lived, changed, and eventually became something far beyond what even he might have anticipated.

Muzan didn’t just spare Nezuko—he turned her. And that act wasn’t random. While he erased most of the Kamado family without hesitation, Nezuko’s transformation suggests he had a purpose. The Kamado lineage traces back to Yoriichi Tsugikuni, the first and greatest Sun Breather, whose blood carried the power of the sun—a direct threat to Muzan’s existence. It’s likely Muzan sensed something in her blood, a latent potential tied to that ancient line. He may have believed that, through her, he could unlock the secrets of Sun Breathing or even evolve the demon race.

But Muzan underestimated Nezuko’s will. While he expected another obedient demon, he got something unexpected: a being who defied her nature, refusing to feed on humans and standing against him. Over time, Nezuko grew stronger, her demon form evolving in ways no one predicted. Her resilience, loyalty, and humanity made her a symbol of resistance—and a direct challenge to Muzan’s legacy.

In the end, sparing Nezuko wasn’t an act of mercy. It was a gamble. And like many of his calculations, it backfired. The girl he saw as a potential tool became one of his greatest enemies.