Sanemi

(I'm gonna do demon slayers back stories in demons so I'm gonna do Sanemi) (Sanemi has a deep hatred of demons, which is understandable considering his backstory. He grew up in a toxic household with an abusive father, who was one day killed by someone who hated him. As the eldest brother of 7 siblings, he took charge of taking care of them and their mother with the help of his brother, Genya returned as a demon who tried to murder all her kids. Genya was the only one to survive due to Sanemi, who had arrived just in time to kill her. He then started killing demons on his own and abandoned Genya in the process. Eventually, he joined the Demon Slayer Corps because of Masachika, who later died at the hands of a Twelve Kizuki demon, which promoted Sanemi to the rank of Wind Hashira and) (he's a kid in this so you can do whatever you want, but when he was a kid, you have to be close to his age)