Haruka Shiraishi: Muzan's Daughter.
While it is not explained in the anime why he did so, Muzan is shown to be living a normal life as a human. Not only that, he's married a woman and has a child with her. The most logical conclusions would be to either blend in society as a human, or to use the woman because of her social standing.
For those who have watched only the first season of the anime, they will be surprised to know that Muzan turns into a woman in the second season. He keeps transforming in order to hide his true identity, and he's even known to change into an 11-year-old child to hide from Demon slayers.
Danny Kibutsuji is the son of Muzan and a human, but Danny's mom ran away. She went into hiding as years pass died, and Danny was left alone. Danny would walk by himself until he meet a man named Yoriichi Tsugukini. Yoriichi knew Danny was a demon, but couldn't bring himself to kill him.
Muzan's surname Kibutsuji means "demon dance" (鬼舞) (kibu) and "street, crossroad" (辻) (tsuji).
Muzan himself never thought highly of Daki and didn't reciprocate her devotion whatsoever, only ever talking to her to sweetly manipulate her into defeating Demon Slayers on his behalf.
In reality, he killed her husband and got close to her because her family was influential. He also got adopted into a rich family by taking on the appearance of a child. Muzan would always target influential families to live well-respected lives without slayers bothering him.
Over his long lifetime, Muzan had a number of families. This includes the one he was born into before becoming a demon. Additionally, he took 5 wives, making each one's life miserable.
Yoriichi was powerful enough to defeat Muzan; however, he couldn't do so. That's because he couldn't come down to kill his twin brother, leading to his own demise. Even to this day, Muzan is scared of Yoriichi.
The only reason why Muzan hates Doma is because of his insincerity and lack of emotions. This might sound odd, expecting emotions from a demon, but even a demon has to retain such tendencies to keep things in order.
Abilities. Demon Body: Unique from other demons, he possesses seven hearts, and five brains. These are responsible for his powerful vitality, should any of them be harmed, he will be severely weakened.
After he neutralizes Tamayo's poison and emerges from his flesh cocoon, Muzan's hair grows in length and turns white due to Shinobu's poison accelerating his age. He also grows numerous mouths all over his limbs, each one lined with a set of incredibly sharp fangs.
Since Muzan favored Gyutaro so much, he chose to incorporate the latter's sister Daki as well. The demon king believed that she was the only tool that could be used to control Gyutaro.
3 Muzan Mainly Liked Daki Because Of Her Potential To Earn Money.
The warrior Muzan feared was a swordsman named Yoriichi Tsugikuni. Yoriichi was the only slayer before Tanjiro who came close to killing Muzan, and the flashback of their fight occurred in Chapter 187.
As the battle reached its climax, Tanjiro was able to knock the doll's head off and discovered that the mechanical body contained a mysterious sword. Fans of the manga will recognize this sword as the one carried by Yoriichi Tsugikuni himself.
Many Kimetsu no Yaiba fans deduce that Yoriichi is Tanjiro's father, but that isn't the case. However, Yoriichi is responsible for teaching Tanjiro's ancestors the Hinokami Kagura, which has been passed down for generations.
Since he didn't know anything about the Blue Spider Lily medicine, he needed others to find the plant for him by happenstance. This is the general reason why Muzan turned Nezuko into a demon. More specifically though, was the fact that Nezuko was of Kamado blood.
Muzan's loyal wife and daughter seem like convenient test subjects to help him synthesize a cure for sunlight weakness as a backup in case the Blue Spider Lily is never found. The young girl might even be Muzan's biological child, a half-demon who gives off the scent of a human while having his essence in her.
It is revealed that Muzan's true fear of dying and immense desire to live and survive was due to him being born "dead," where his heart would constantly stop in his mother's womb and was assumed stillborn until he fought to breathe before his cremation.
14) Muzan Kibutsuji (over 1000)
Being a demon, Muzan is capable of living for many, many years. However, unlike other demons that have aged over hundreds of years. Muzan is well over 1000 years old.
Kibutsuji Muzan, Demon Slayer's King of Demons, has few weaknesses, but he still must hide from the sun. For the centuries he has been alive, Muzan's goal is to concur death and live eternally.
Origin. The first demon that is said to have existed was Muzan Kibutsuji. The one who turned him into a demon was a generous doctor from the Heian Period, who wanted to save Muzan from death since, at the time, he was diagnosed with a disease which would kill him before he turned twenty.
Despite being the unstoppable force of nature in Demon Slayer, Muzan is still incapable of conquering the Sun.