The story follows Kamado Tanjiro, a young boy whose family is killed by a demon, leaving his younger sister Nezuko as the only survivor, turned into a demon herself. Tanjiro vows to become a demon slayer and find a way to turn his sister back into a human. He undergoes the selection exam and is accepted into the demon slayer corps. Tanjiro and his comrades go on various missions, facing powerful demons and learning from the Hashira, the strongest demon slayers in the corps, about the importance of teamwork, never giving up, and accepting oneself and others for who they are. They also discover the secret of the Breath of the Sun, a powerful technique used by the demon slayers of the past. In the final battle, they face off against the Upper Moon demons and the demon lord, Muzan Kibutsuji, fighting together to protect humanity.
Tanjiro meets the Hashira, the strongest demon slayers in the corps, for the first time. He is in awe of their power and skill, but also learns of their flaws and struggles.