Demons are the cause of all of humanity's troubles in Demon Slayer. They're evil entities who feed on human blood, and who only seek to hunt down human beings as their prey. However, the most important demon in the series isn't at all like her demon counterparts. Despite having been turned into a demon, Nezuko doesn’t follow the same rules as most other members of her race do.
Source：https://www.cbr.com/demon-slayer-nezuko-kamado-demon-form-facts-trivia/
