HELLO!!! NEW VIDEO!!! I hope you like it a lot!! Here is the au for context
Giyuu and Megumi are only siblings on Toji's side, which means they have different mothers. Tsumiki doesn't exist here, only Tsutako exists. Toji abandoned Megumi with Giyuu and Tsutako when Megumi's mother died, since then they lived together until the unfortunate case of Tsutako's death happened, when they went out to tell the villagers they didn't believe them both so Giyuu grabbed Megumi's hand and they ran away from there, until Urokodaki found them and "adopted" them (and there they began to know more about demons) there they both met Sabito although Megumi was never as close to him as Giyuu but he still liked him. When Giyuu and Sabito went to the final selection, Megumi stayed with Urokodaki, two weeks had passed and Giyuu had not returned so he became desperate but he kept waiting, then he received the news that Sabito died but Megumi being a little boy also thought that Giyuu had died so he ran away from Urokodaki's house. When Giyuu returned to Urokodaki's house he found the bad news that Megumi had run away from there, Devastated by the loss of his younger brother, Giyuu carries with him the weight of guilt, believing that his absence and the pain of Sabito's death led Megumi to an unknown destiny. Megumi wandered around for several days until Gojo found him before the zenin and took him in.
What are demons in this Universe?
Well, they are almost the same as in the original, except that Muzan, their creator, was a special grade curse with a peculiar technique: being able to create entities with his blood. So demons are a type of curse not created by the negative energy of people but by Muzan, but these are not curses in themselves and have many more weaknesses than curses, such as the sun and the nichirin swords
What about the demon slayers?
They have existed for a long time, they are a secret organization just like Jujutsu Tech among others, but they only focus on eliminating all the demons that have been created by Muzan and Muzan himself. The sorcerers have no idea of the demon house organization since they remain well hidden, not even the high command knows of their existence.
What are the Respiration techniques like in this au?
Well, they use the base of cursed energy to be able to bring them to life, that simple.