Why did Muzan Kibutsuji turn Nezuko Kamado into a demon at the start of ‘Demon Slayer?’

Warning: The following article contains spoilers for Demon Slayer.

In the first episode of Demon Slayer, the main characters and sibling duo Tanjiro and Nezuko Kamado are forced to wrestle with the tragic aftermath of their family’s horrific deaths and the girl’s transition to demonhood, owing to a demon attack that seemingly came out of nowhere. However, by Demon Slayer‘s seventh episode, they eventually come across demon-overlord and -progenitor Muzan Kibutsuji, who happens to be the responsible party. After that mystery is cleared up, the big one that remains for a while is why he did it.

Why, indeed? What reason did Demon Slayer‘s big bad have for offing most of the Kamado family and turning Nezuko into a demon? Was it just a random attack, or was a specific purpose involved? Does he have some special use for the black-haired, pink-eyed demon? And if so, what is it?

Muzan’s reason for turning Nezuko

It turns out that Demon Slayer‘s arch-villain started out life as a sickly boy who was always at the point of death. However, his health problems were “fixed” after he was turned into a demon in a medical experiment gone wrong. That being said, notwithstanding the myriad of abilities Muzan’s demonic state afforded him, along with his lack of concern about the less-than-ideal side effects (such as now having a craving for human flesh), he lacked the ability to walk in the sun.

To attain sun tolerance and hence, an ideal immortal body, Demon Slayer‘s arch-villain knows that he needs to consume The Blue Spider Lily flower (a mysterious ingredient required to complete his medication, which he murdered his doctor before he could receive) or a sun-tolerant demon. Thus, desiring to become a perfect being with no hang-ups, he keeps creating more demons by feeding human victims his corrupted blood, hoping that at least one of them will help him find the desired plant or prove capable of withstanding the sunlight.

Tragically for him, the flower only blooms during the daytime two or three times a year for a short period of time, making the creation of a demon who can handle sun exposure his best bet.

Sadly, the Kamado family were random victims of this relentless quest. Unfortunately for the demon lord, he left the residence assuming they had all died as experimental failures, leaving newly awakened (and eventually sun-tolerant) demon Nezuko in Tanjiro’s safe hands.