These flowers are Blue Spider Lilies and are very important to Muzan Kibutsuji, the anime's prime villain. Not only are they indicative of his past, but of his present hopes and desires as well. The story focuses on Tanjiro and Nezuko Kamado, siblings in a seemingly mundane family with a mysterious heritage.
Demon Slayer hints that consuming the Blue Spider Lily can negate a demon's vulnerability to the sun, which is why Muzan spent ages hunting for the bloom. As the strongest being in the world, Muzan's only weakness is the sun.
In some cases, depending on the climate, the Blue Spider Lily didn't even bloom at all. This explains why Muzan never found it, as he would have been unable to go out during the day.
The Blue Spider Lily is an important ingredient in the medication prescribed to Muzan during his mortal days. It is the very medicine that allowed him to become a demon. Since Muzan isn't the one who created the medicine and he ends up killing his doctor, he has been in constant search for it.
The spider lily is part of this rich flower language and often is used to foreshadow a coming death. Red spider lilies can be seen in passing in one of my favorite shows, Kimetsu no Yaiba (鬼滅の刃) or Demon Slayer in English, in the ending credits. In a show full of death, it's not just foreshadowing, but a promise.
Black. Toho Co., Ltd. Black is the most mysterious color of all the blades, and is held by the main character, Tanjiro. It is a rare blade and represents the sun; it also holds a theory that the demon slayers who own this sword are not to live a long life.
Muzan's ultimate goal is to attain an immortal body. He wanted to be able to walk in the sunlight and live forever. In order to gain this, he needed two things: the Blue Spider Lily and the body of a demon who could withstand the sun.
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.
Demons cannot have offspring (if they do have kids and descendants it was before they became a demon, the child is most likely not Muzan child.
It's true that in later episodes, Muzan also appears as a woman wearing a kimono when he's holding court over other Demons, most of whom are also wearing traditional Japanese clothing. This might have something to do with Demons (or “Oni”) themselves being part of traditional Japanese culture.
The two known demons who broke free of Muzan's curse are Tamayo and Nezuko. Tamayo was able to break free of the condemnation when Yoriichi fought Muzan, nearly killing him in the process. During this weakened state, Yoriichi let Tamayo go, free her from Muzan, and free her from the curse.
When Demon Slayer's Tanjiro met Muzan in Tokyo, Muzan had a human wife and daughter with him. There's a chance he genuinely cared for them.
Yoriichi combined all his forms into one strike and turned his blade bright red, enabling him to cut through all of Muzan's weaknesses and overpower him.
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.
During his final struggle, and as a way to slow down the effects of the sunlight, Muzan adopts an enlarged demonic infant form, approximately as tall as a 3 story 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.
However, she wasn't immune to the sunlight initially, as she got burned badly at first. So, in conclusion, her coming from a Sun Breathing user's lineage and not relying on human substance are perhaps the reasons for her immunity.
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. Repeated abuse and torture drove them to take their lives.
Haruka Shiraishi: Muzan's Daughter.
Personality. Anne was a kind and loving soul and was described as the only person that Muzan had truly loved, besides his three daughters.
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.
Don't go! DON'T LEAVE ME HERE! Muzan speaks his final words as he loses control over Tanjiro.
Muzan is Demon Slayer's strongest demon, but is oddly afraid of Tanjiro's earrings. The history behind them reveals what happened in Muzan's past.
Lycoris radiata, known as the red spider lily, red magic lily, corpse flower, or equinox flower, is a plant in the amaryllis family, Amaryllidaceae, subfamily Amaryllidoideae. Originally from China, Japan, Korea and Nepal and from there to the United States and elsewhere.
Blue lily may refer to the following plant species: Agapanthus praecox, native to South Africa and widely cultivated. Nymphaea caerulea (Blue Egyptian water lily or sacred blue lily), native to East Africa and widely cultivated. Nymphaea violacea, a species of waterlily native to northern Australia.