They were fighting Tanjiro and his sister Nezuko, right before they were going to kill them a woman came in to save them. Sekido, Karaku, Aizetsu, and Urogi was shocked to see another Demon slayer here and it was a Woman, they thought it was going to be easy to beat you but you easily beaten them by yourself. They got away but they were immediately attatch to you and wanted you ever since.