Why is Wisteria poisonous to demons in Demon Slayer?

Demon Slayer: Kimetsu no Yaiba features a lot of vicious demons who are terrifyingly strong and harder to subdue. Even the likes of the Hashira have to give their everything and drive themselves to the point of overexertion to match up with these demons.

The more a demon devours humans and assimilates the powerful blood of their progenitor Muzan Kibutsuji, their capabilities and strength increase to another level.

As everything has its weaknesses, a few things are lethal for the demonkind, like Nichirin blades, sun, and a unique flower named Wisteria. Fans of Demon Slayer are perplexed by how a flower could lead such immortal beings to death.

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What is a Wisteria Flower and how is it lethal to demons in a Demon slayer?

Although the Wisteria flower has multiple properties, it is most prominently used for making poisons that can incapacitate regular demons and the Lower Ranks of 12 Demon Moons. Being the progenitor of all the demons in Demon Slayer, Muzan Kibutsuji is the only individual who is insusceptible to its effects.

Wisteria flowers in real life are also toxic, but for everyone. The seeds of this flower contain a toxic compound called the wisterin, which, if ingested, may cause dizziness, nausea, collapse, etc. In the Demon Slayer universe, these flowers are lethal only to demonkind and can create a much more adverse effect than just dizziness and nausea.

The Insect Pillar Shinobu Kocho has shown greater proficiency in Wisteria flowers. For starters, her Nichirin blade is modified into a Rapier that is soaked with her own specialized version of highly concentrated Wisteria poison.

Being the most intelligent member of the Demon Slayer Corps, Shinobu has shown exceptional mastery over her personally devised poisons.

A normal dose of Wisteria poison on demons could hinder their abilities like regeneration, movement, suppressing their extrasensory perception as well as weakening their Blood Demon Art.

Before her fight with Doma, Shinobu, with the help of Tamayo and Yushiro, turned herself into a walking capsule of poison for demons. Every cell in her body is coated with Wisteria poison, making her the only human a demon should avoid consuming.

She even relayed the details that, with her overall body size and weight, she is 37 kg worth of poison, which makes her 700 times more lethal. With this amount of dosage, Shinobu can even bring down the powerful Upper-Rank demons.

Wisteria flowers are lethal to demons but are a blessing to humans. The flowers also consist of a unique medication property that would turn a demon back into a human. Shinobu, over the course of a period, has perfected her experiments with the flower to create a plethora of antidotes that can repel the effects of poisons from any kind of demon.

As seen in Demon Slayer, when Zenitsu got poisoned by the Spider demon (Son), Shinobu, with her unique antidote, saved the life of the former in an instant. Shinobu carries her medicinal pouch composed of syringes filled with Wisteria antidotes with her all the time.

An unknown family was saved by Demon Slayers, so to express their gratitude, they created a family crest with the Wisteria flower so that Corps members could easily identify these houses with the crest and stay there, free of cost.