The Truth Behind The Blood Demon Art In Demon Slayer
"Demon Slayer: Kimetsu no Yaiba" has become a massively popular international hit. The manga-turned-anime tells the story of Tanjiro, an ordinary boy in Taisho-era Japan whose life is turned upside-down when a demon kills his family. His only surviving sibling, little sister Nezuko, is turned into a demon. But somehow, she retains a portion of her humanity. Tanjiro vows to slay the demon that wrecked his life and cure his sister of her possession.
The demons of "Demon Slayer" are, in fact, not demons. They are oni, Japanese monsters whose names are translated into English "as 'demon,' 'devil,' or 'ogre," according to the Book of Yokai. They act most like kyūketsuki, a blood-sucking subspecies of oni — vampires, in essence. And, like western vampires, they are vulnerable to sunlight. To slay a demon, you can decapitate them with a sword made of special metal, inject them with a derivative of wisteria, or expose them to sunlight. But that's not all that sets these demons apart. Many have something called blood demon art, a special power with a hidden truth.
Blood demon art offers a peek at a demon's personality
In "Demon Slayer: Kimetsu no Yaiba," demons develop blood demon art when they consume enough humans. The blood demon art is unique to each demon, and especially powerful demons can have multiple blood demon arts. Tamayo, a very high-level demon who managed to break free from Big Bad Kibutsuji's control, can use her own blood to create spells. This could be because she was Kibusuji's lieutenant back in the day, and absorbed some of his power.
Blood demon arts also often draw on a character's innermost being or pre-demonic history. Kyogai had a drumming blood demon art because he was a drummer in life. Nezuko's blood demon art is only dangerous to demons, highlighting her alignment with the Demon Slayer Corps. Susamaru, an incredibly childish demon, could summon lethal temari. (Can you imagine getting killed by a demonic hacky sack? Oh, the indignity of that.)
Blood demon arts are also conjured from the demon's own blood. This could be another reason why each art is so personal to the particular demon. The power comes from their own flesh and blood.