How Demon Slayer's Muzan Originally Became The First Demon (2024)

Warning: Contains Spoilers for Demon Slayer's MangaThe big villain of Demon Slayer, Muzan Kibutsuji, isn't just the mastermind behind a lot of the plots that the heroes try to stop; he's also literally the origin of nearly every demon they encounter, as a result of his ability to create more demons. But if Muzan created all the other demons that are shown in the series, who created Muzan?

Though Demon Slayer is set in the early 20th century, Muzan has been shown alive in flashbacks as far back as 1,000 years ago. He creates other demons by giving his blood to humans, causing them to transform and gain incredible powers--provided they can handle the mutations.

If they can't, their body will simply be reduced to a pile of goo before turning to dust. Muzan extends a surprising amount of control over those who he has transformed, able to kill them with ease simply for things like speaking his name.

Demon Slayer's Muzan Became a Demon on Accident

An Experimental Treatment Meant to Save His Life Transformed Him

See Also

Does Tanjiro Turn Into A Demon In Demon Slayer: Kimetsu No Yaiba? - AnimehunchDoes Tanjiro Become a Demon In Demon Slayer?Demon Slayer: How Muzan Kibutsuji Became the Demon KingDemon Slayer ending explained: What happens - and who survives - in the manga's final chapters?

In chapter 127 of the Demon Slayer manga, it's revealed that Muzan wasn't always a demon, but he was always a pretty bad guy. Like most other demons, Muzan started out as a human, but since he was the first, there wasn't simply a demon who could give him blood and cause him to transform. Muzan's transformation into a demon was actually a complete accident. In the early 900s, 1,000 years before the story, the human Muzan was dying of an unspecified illness and decided to undergo an experimental treatment in an attempt to save his life.

The experimental medicine was made out of a flower known as a Blue Spider Lily, a rare plant that's scarcely more than a myth. While the medicine seemed to heal him, he was unable to go back out into the sunlight again and began exhibiting other signs of being a demon. In a rage, Muzan killed the doctor who created the original medicine but was left with no way to tolerate sunlight as a result.

Muzan's Ultimate Goal in Demon Slayer Is the Blue Spider Lily

Since then, Muzan has attempted to do two things. The first was to create more demons by sharing his blood, in the hopes that one of them would mutate in such a way as to be able to withstand sunlight, allowing him to learn the secret from them. The other was to search out the Blue Spider Lily, in hopes of recreating the original serum which transformed him and possibly regain his ability to go out into the sunlight. This is also why Muzan is shown to have an interest in chemistry and science at various points throughout the manga--he's spent the past 1,000 years learning anything that might help him to overcome this weakness.

Despite all of this, Muzan doesn't want to go back to being one of Demon Slayer's humans; having already once lived with the specter of death hovering over him, he refuses to do so again, instead questing to remain immortal by eliminating his one significant weakness.

Muzan's motivations and backstory are more complex than one might expect from a villain who is so cold and cruel, but that's Demon Slayer. The ultimate irony is that the Blue Spider Lily only blooms in the day, and even then very rarely, so no matter how many thousands of years Muzan looked, he never would have been able to find it in Demon Slayer.

How Muzan's Origin and Motivations Makes Him Tanjiro's Opposite

Tanjiro Displays Shockingly Merciful Kindness While Muzan Turns Fully to Evil

Tanjiro and Muzan contrast very starkly with each other, in their motivations and origin stories. Muzan's villain origin story explains why he became so frustrated with his circ*mstances and turned to evil. Transforming into a sunlight-averse demon suddenly would be enough to upset anyone. However, Tanjiro suffered upsetting circ*mstances outside his control too, arguably to an even worse extent than what Muzan dealt with.

Tanjiro lost almost everything. His entire family perished at the hands of demons at a young age, leaving him and Nezuko as the sole survivors. He also faced an entirely new problem: figuring out how to turn Nezuko back human after she became a demon. His journey as a demon slayer was rife with struggles and pain, as he became physically injured and emotionally devastated at every turn. Friends and mentors died right before his eyes and, at times, he felt he was doomed to fail.

However, the key difference between Muzan and Tanjiro is how they handled the difficult hands they had been dealt in life. Muzan turned to evil, slaughtering droves of innocent humans in his pursuit of a cure for his demon ailment. However, Tanjiro takes a kindhearted and gentle approach, fighting to help humanity in spite of his inner pain and even showing mercy to the very demons who killed his family and transformed his sister. This stark difference makes Tanjiro the hero and Muzan the villain of Demon Slayer.

Demon Slayer: Kimetsu no Yaiba

TV-MA

Animation

Action

Adventure

Demon Slayer: Kimetsu no Yaiba follows Tanjiro Kamado, a young boy who becomes a demon slayer after his family is slaughtered and his sister Nezuko is turned into a demon. Tanjiro embarks on a perilous journey to find a cure for his sister and avenge his family, facing numerous demons and formidable opponents along the way. Set in Taisho-era Japan, the series combines intense combat sequences with intricate character development.

Cast

Natsuki Hanae , Zach Aguilar , Abby Trott , Akari Kitō , Yosh*tsugu Matsuoka

Release Date

April 6, 2019

Seasons

5

Main Genre

Animation