The Kibutsuji Curse: Why demons can't say Muzan's name in Demon Slayer

The main antagonists in Demon Slayer are Demons, a race of ancient, vampire-like creatures with a wide variety of supernatural powers. These powers range from the ability to change the spatial orientation of their home to the ability to create spider threads harder than iron.

Demons can only be killed by sunlight or by Nichirin Swords that have the property to absorb sunlight. Wisteria flowers are also believed to be poisonous to them. The only way to kill a Demon permanently is to decapitate their heads or subject them to the sun.

All Demons abide by one simple rule. They never speak their leader’s name or else they will be killed. This is called the Kibutsuji Curse, which is forced upon them by their leader.

Disclaimer: This article contains spoilers for Demon Slayer. Please read at your own risk.

Note: This article solely reflects the opinions of the writer

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Demon Slayer: The Kibutsuji Curse explained

The Leader of the Demons in Demon Slayer is the first of his kind, a man (and sometimes a woman) named Muzan Kibutsuji.

Muzan was born sickly in the Heian period of Japan, which, for reference, is from 794 AD to 1185 AD. He suffered from a sickness that almost killed him at birth.

It was only after he received a special unfinished treatment from a doctor that he was able to survive. In the process, he became the first Demon in the series.

In order to create new minions, Muzan has to give them some of his blood. This, in turn, lets him place the Kibutsuji curse on them.

The Kibutsuji curse happens when one of his minions speaks Muzan's name, “Kibutsuji,” aloud. When they do this, three arms will sprout from their bodies and tear them apart.

The curse has two triggers. The first is the spoken word, and the other is Muzan himself. He can trigger the curse whenever he wants.

This happened to Susamaru, one of the enemies introduced in the show. She spoke his name by accident and was killed for it despite having no ill intentions or any signs of disrespect.

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Why does Muzan curse his demons?

Muzan is, for lack of a better term, cowardly. Despite being the first-ever Demon with a massive amount of power, Muzan rarely, if ever, has a direct hand in the events of the series (save for the inciting incident).

Many of his powers are built to keep himself alive due to an overwhelming fear of death. These include specializing in long-range whipping attacks with his arms and being able to survive even if one part of him is still working. He has a myriad of other backup plans that enable him to avoid death for as long as possible.

Muzan’s fear of death came from his sickly existence as a human, as he was on the verge of it constantly. This resulted in an obsessive, narcissistic personality that manifested in sociopathic tendencies.

This was demonstrated when he first received his treatment. When the treatment initially appeared to have failed, Muzan killed the doctor and didn’t show an ounce of regret over it.

The curse he places upon his minions is a way of safeguarding his own continued existence. While smug and arrogant, Muzan dreads facing any Demon Slayer and avoids conflict at any turn. Even when faced with Tanjiro and Giyu, he would rather they stop fighting him and just “earn their wages.”

In addition, due to his extreme narcissism, he does not tolerate dissent in any way. His ego is so great that he perceives nearly any action to be a slight against him. As such, he does not allow his subjects to rebel against him in any way, shape, or form.