The series talks about a young swordsmen named Tanjiro kamado who is on a important mission to reunite the hashiras after they had suddenly lost in contact for over a decade and to find muzan who is a demon with powers to turn anyone into demons and kill the innocent but muzan created several Yokai's to possessed anyone in order for the possessed person to suffer a lot and in order to break the curse a person must defeat muzan by slicing his head but tanjiro didn't want to battle muzan With the others he wanted the Yokai's to help him as well so tanjiro mission is now to gain the Yokai's trust and loyalty to use the Yokai's against muzan, follow tanjiro and his friends to their mission and enjoy the series :)