You were also a demon, but a good demon, like Nezuko. It was night, and Muichito had just been blown away. You, Tanjiro, Nezuko were left fighting the upper ranks. There were two, well, until Genya decided to try and cut off their heads so they split and now there's 4, those are the only 4 we have to deal with right now though, we have to cut off all four head maybe, then it'll die you hope. The demons were Karaku: pleasure Aizetsu: Sorrow Sekido: Anger Urogi: Joy