Blue Spider Lily Meaning in Demon Slayer

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The Blue Spider Lily in Demon Slayer refers to the mythical plant used to treat Muzan for his terminal illness when he was still a human. However, because the treatment was incomplete, Muzan turned into a powerful Demon who craved human flesh and was vulnerable to the sun instead of being cured. 

The Blue Spider Lily

The Blue Spider Lily is a variety of the Red Spider Lily in the Demon Slayer universe. Its special characteristics include its unique indigo color, the time it blooms, and its ability to enhance the human body to a cellular level. The plant has a super-regenerative ability that, when applied to humans, becomes immortal. 

The Blue Spider Lily only blooms during the day for a few hours and goes back again to being a plant resembling a horse-tail. The end chapter also reveals that the plant only blooms 2-3 days per year which explains why Muzan and his demon minions could never find the plant since demons can’t walk under the sun.

The manga also revealed that the Blue Spider Lily plant grows only in specific places, especially in soils where people have recently died. However, there are also other special requirements for the plant to remain alive as it is very sensitive. 

Only Muzan’s healing priest and Tanjiro’s mother know where the Blue Spider Lily continuously grows. 

You can check out our other article about The Red Spider Lily to know the significance of the plant in Japanese culture. 

Muzan and his illness

Shvieiart 8 X 12 Metal Signs - Muzan Kibutsuji Demon Slayer Vintage Look Metal Tin Poster

During his human life, Muzan suffered a terminal illness that prevented him from achieving his desires and fulfilling his duties as a son of a prominent family in the Heian period, Japan. His fear of death caused him to become crueler and more impatient. 

While on his deathbed, the young Muzan has ordered his healers to find every solution they can think of to cure his terminal disease. The person leading Muzan’s treatment knows about a special treatment using a mythical plant that is difficult to find, the blue spider lily. 

According to the said priest/doctor, the Blue Spider Lily can cure terminal illnesses, strengthen the physical body of the patient, and can even prolong a lifespan. However, the head priest/doctor warns Muzan that not only could the treatment be life-threatening, but it could also result in losing one’s humanity.

Despite the warning, Muzan told the healing priest to get the Blue Spider Lily as he considers it his only chance of survival. Eventually, the priest brought to Muzan the said Blue Spider Lily, and immediately, it was turned into medicine.

After Muzan’s healing priest administered the treatment using the Blue Spider Lily, Muzan got impatient as he didn’t feel better but instead got worse. He killed the person treating him before the treatment was over. After a few days, Muzan turned into a demon who couldn’t go out in the sun. 

He realizes that he needs the Blue Spider Lily to complete his transformation. Unfortunately, the only person who knows about the Blue Spider Lily, where it can be found and how to use it is the person he killed while being treated. 

Muzan and the Ubayashiki Family

In Chapter 137 of the Demon Slayer Manga, Muzan visited the head of the Ubayashiki household, Kagaya Ubayashiki, on his deathbed. Muzan knows that Kagaya only has very little time as the curse consumes Kagaya’s body. 

Muzan and Kagaya talked and expressed how they felt about each other. As they exchanged sharp words, Muzan revealed his relation to the Ubayashiki family.

Apparently, Muzan is Kagaya’s ancestor. Muzan used to be the heir of the Ubayashiki family before he became a demon.

Kagaya revealed that his family learned about the nature of their family’s curse because of a priest. The curse runs on every Ubayashiki bloodline, and it’s supposed to kill all family members to extinction. 

The priest also told them that the reason why the members of the Ubayashiki family die early is because of the demon that came from the Ubayashiki bloodline. The Ubayashiki household is then given wives by the priests to strengthen the bloodline making the Ubayashikis more resilient to death. However, it only extends up to 30 years and limits the curse to men, which is why all male Ubayashikis don’t last 30 years old.

The only way to lift the curse is for the demon in their bloodline, Muzan Kibutsuji, to be exterminated. After Muzan is eliminated, those afflicted with the curse will then be able to live a normal life span.  

Since then, the Ubayashikis vowed to kill Muzan and created the Demon Slayer Corps. 


Article by John Salinas.

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