Tanjiro Kamado decided to embark on a journey because his sister Nezuko Kamado was made to be a demon. Then, he entered an organization which is called “Kisatsutai”. People can attend it over an audition, so there are many strong people in it. Begging with Tanjiro and members who have each “breathing”. Tanjiro has breathing of water, Zenitsu Agatsuma who is synchronous to Tanjiro has breathing of thunder, and Inosuke Hashibira who is also synchronous to Tanjiro has breathing of animals. In addition, there are 9 of the strongest slayers who are called “Hashira”. On the other hand, there is the worst and strongest demon which is called Muzan Kibutsuji.