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.
Why does Muzan Kibutsuji cross-dress in Kimetsu no Yaiba? It's not that he wanted to dress as lady, but rather that he was frightened. According to Kagaya Ubuyashiki, the leader of Demon Slaying Corps, nobody in corps ever found Kibutsuji before Tanjiro did.
During his final struggle, and as a way to slow down the effects of the sun, Muzan adopts an enlarged demonic baby form, approximately as tall as a 3 floor building when standing up. In this form he has very pronounced blood vessels across his body, small claws in his hands and fanged teeth in his mouth.
Muzan keeps changing his appearance in Demon Slayer as a form of fear. Despite having tremendous powers, Muzan from Demon Slayer is far from being omnipotent. He is consumed by his fear of Yoriichi Tsugikuni. On top of that, he will disintegrate as soon as he steps into the sunlight.
Muzan Kibutsuji (鬼舞辻無惨) is the man responsible for transforming Nezuko Kamado into a Demon and the main antagonist of Demon Slayer (Kimetsu no Yaiba). Tanjiro could identify him instantly, based on his demon smell. He was the first human to become a Demon over a thousand years ago.
Here Muzan is seen in his true, Demonic form.
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.
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.
2 His Body Is Weak To Certain Poisons
Poisons that did not exist before, like Tamayo's concoction of turning demons into humans, are the kind of poisons that Muzan's body isn't prepared for, as he's never been exposed to them before, and thus, his body has no idea as to how it should fight those poisons.
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.
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.
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 the "Demon Slayer" anime series, demons cannot say the surname "Muzan" because it's forbidden in their society. Muzan Kibutsuji is the main antagonist of the Demon Slayer anime series, and he is the founder of the demon society and the source of the demon curse that plagues humanity.
Therefore it is quite evident that Muzan doesn't love his family. They are merely tools to achieve his goal of true immortality and wreak havoc in the years to come.
As mentioned, a lady and a child made an appearance with Muzan in episode 8. They were his human wife and daughter. The two were never seen again after that episode.
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.
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.
Tanjiro Kamado
Tanjiro is considered to be Muzan's main nemesis throughout the series.
Muzan's Blood Demon Art is known as “Biokinesis.” It allows him to alter his body and shapeshift at will. Although all demons have this innate ability, Muzan elevates it by modifying his flesh and organs. Biokinesis is also the only reason Muzan has been able to hide from the Demon Slayer Corps for 1000 years.
In episode 6 of Demon Slayer season 2, Nezuko entered a berserk state to protect her brother Tanjiro, causing her body to develop into that of an adult. She loses her gag, grows a single horn and gains vine-like patterns across her body.
Muzan Kibutsuji has done some terrible things in Demon Slayer, but his slaughter of Tanjiro's family is one of the most mysterious.
Muzan refused to die and when he was finally about to breathe his last, he transferred all the blood to Tanjiro in the hope that he would become the successor and carry out his will.
Haruka Shiraishi: Muzan's Daughter.
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.