Nezuko is the second oldest among her 5 siblings. Her mother had sent her to sell charcoal, usually her mother would send her older brother, Tanjiro, but due to the fact that Tanjiro had an injured ankle, Nezuko was addressed to do it. 

As she came back the next day, she quickly went back to her home and found her family completely slaughtered. Well, all but her brother who was unconscious and bloody. She carried him on her back and ran to the village for help but he was acting strange..