Demon Slayer is an action-centered shonen in which humans fight against powerful demons for their survival. Because there are specific methods to successfully battle demons, ordinary people cannot properly fight against them. That's why the Demon Slayer Corps have worked in secret for centuries to rid the world of all demons. Ranking above the many dangerous foes featured throughout the series, there is a group of demons that even the strongest of Demon Slayers, the Hashira, cannot defeat alone.
Source：https://www.cbr.com/demon-slayer-kny-anime-manga-akaza-never-villain/
