Muzan is undoubtedly the strongest demon in the entire Demon Slayer series. He is also the first ever demon to come into existence and has the power to turn regular human beings into flesh-eating demons.
During the first few episodes of Demon Slayer, Tanjiro witnessed some of the most scarring and traumatic events that would have taken place in his life. His entire family was slaughtered and his sister was turned into a demon. Since then, fans wanted to know why Muzan let Nezuko live while the rest of the Kamado family members were killed.
Disclaimer: This article contains major spoilers from the manga.
Demon Slayer: Why did Muzan let only one member from the Kamado family live?
Muzan was a human who turned into a demon when his medication was incomplete. He turned into a flesh-eating being with enhanced physical abilities and regeneration rates.
This took place in the Heian period and since then, he proceeded to regularly consume human flesh and turned human beings into demons. His goal was to find a permanent immunity to sunlight which would let him live forever and become invincible.
He knew that the Kamado family practiced the Hinokami Kagura which was associated with the Breath of the Sun. Therefore, he decided to kill everyone in the family since they would get in his way of achieving his goals. Fans later questioned the reason for letting Nezuko live. Fans believed this could have been a strategic move from Muzan.
The theory states that Muzan wanted to create a demon that developed an immunity to the sun. Upon doing so, he would consume the aforementioned demon and become invincible. Since members of the Kamado family have been practicing some form of the Breath of the Sun, Muzan attempted to create the perfect demon by turning Nezuko into one.
There was some merit to this strategy since Nezuko was able to develop immunity to sunlight which was featured in the fight against Hantengu. Nezuko initially suffered from a bad burn, but eventually was able to resist the effects of sunlight.
That being said, Muzan didn’t really succeed in achieving his goals as Nezuko turned into a human with Tamayo and Shinobu’s help. Following that, Muzan was also defeated by members of the Demon Slayer Corps.
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