The Demon Slayer Corps... An organization that's been hunting down demons since ancient times. Sakonji Urokodaki starts training Tanjiro for Final Selection, the test for joining the unit. Navigating a mountain riddled with booby traps, dry sword swings, waterfall immersion and breathing techniques... A year later, Urokodaki informs Tanjiro that he has nothing more to teach him, and gives him one last hurdle to overcome in front of a giant boulder.

Tanjiro is now clad in the uniform of the Demon Slayer Corps. His Nichirin Sword on his hip, and Nezuko, now awake, in a special box made by Urokodaki on his back, he heads out for his first assignment. A town to the northwest where girls have been vanishing nightly. There, Tanjiro meets Kazumi, haggard with worry after his girlfriend's been abducted. Though he does catch the scent of a demon nearby, there's just no demon in sight. Tanjiro is sure that a demon is behind this sinister incident...

Now split into three, the demons have driven Tanjiro into a corner. It is then that Nezuko attacks. Now that she’s become a demon herself, she’s no longer so weak that she needs protection. His mind made up, Tanjiro follows one of the demons into the swamp now spreading across the ground. Waiting for him there is...

Every time Kyogai, the master of house, plays his tsuzumi, the room spins and Tanjiro struggles. Debilitated by the fractured bones he sustained in his previous battle, Tanjiro tries to fire himself up as he desperately fights on, but he is overwhelmed by Kyogai's Blood Demon Art. Will he find a way to slice off Kyogai's head?

Tanjiro and Inosuke battle the Demon Slayers trapped by spider webs. After slashing the threads and destroying the webs, they head deeper into the mountain. The farther they advance through the forest, the thicker the threads become, and those under their control start moving in ways impossible for a human being. Stopping the Demon Slayers without hurting them isn't going to be easy, but then Tanjiro makes a certain move...

Tanjiro and Inosuke face off against the Father Spider Demon of Mt. Natagumo. Tanjiro unleashes an attack, only to get hurled away by the demon's overwhelming power. Landing near a river, he comes upon the young demon Rui torturing the Sister Spider Demon. When Rui calls their bond of terror and hatred "a family’s bond," Tanjiro is enraged. So begins the battle between Rui and Tanjiro.

Seeing Tanjiro try to protect Nezuko even as he collapses triggers memories of Rui’s own past. Once a sickly boy, he became a demon after meeting Muzan Kibutsuji who gave him a share of his blood. But after he turns into a demon, his own parents try to kill him. Ever since then, he has been searching for a family. Seeking a bond that he can never hope to acquire...

As Tanjiro and the others are devoted to their rehabilitation training, the absolute master of the demons, Muzan Kibutsuji, gathers the Lower Ranks of the Twelve Kizuki. The demons, too, are preparing to make their next move. As training draws to a close, Tanjiro has improved to the point where he can fight on equal terms with Kanao. Just then, he receives word of a new mission from his Kasugai Crow.

Flame Hashira Kyojuro Rengoku receives new orders: Travel to the Mugen Train, where over forty people have gone missing, and conduct an investigation. Leaving the Demon Slayer Corps Headquarters, he sets off on this new mission.

Tanjiro, Zenitsu, Inosuke and Rengoku have fallen into a deep sleep while under the control of Enmu's Blood Demon Art. As Enmu attempts to use his accomplices to destroy the spiritual cores of Tanjiro and his companions in order to defeat them, Tanjiro realizes that he is inside a dream and searches for a way to wake up. In order to awaken from the dream, Tanjiro makes a decision to use his sword to cut into his own neck.

Nezuko, Zenitsu and Rengoku fight against Enmu to protect the passengers. Meanwhile, Tanjiro and Inosuke discover the location of Enmu's neck. They work in tandem to thwart Enmu's Blood Demon Art and sever Enmu's neck. The Mugen Train writhes in pain and derails. What will be the fate of the 200 or so passengers as well as Tanjiro and his friends?

After Tanjiro visits the Rengoku residence and meets Kyojuro's younger brother, Senjuro, to deliver Kyojuro's last message, Tanjiro spends his days training and completing missions. One day, he returns to the Butterfly Mansion to find Sound Hashira, Tengen Uzui, attempting to take Aoi and Naho away on a mission against their will. Tanjiro, Zenitsu and Inosuke offer to go on that mission instead, and they head to their next destination - the Entertainment District.

Tanjiro and Uzui have been separated by Gyutaro’s Blood Demon Art. As Tanjiro joins the struggling Zenitsu and Inosuke, they manage to decapitate Daki at last thanks to their coordinated barrage of sword strikes. However, when Inosuke tries to run off with Daki’s head, he gets pierced by Gyutaro’s scythe. Uzui has also collapsed, leaving Tanjiro and the others with their backs to the wall.

An Upper Rank Demon has been defeated for the first time in a hundred years by Uzui, Tanjiro, and his comrades' effort. This news causes a ripple effect not only among the members of the Demon Slayer Corps, but also the Upper Rank Demons, who have been summoned by Muzan Kibutsuji. Meanwhile, Tanjiro is recovering at the Butterfly Mansion when he discovers that he has upset his swordsmith Haganezuka after chipping his sword and decides to head to the village where the swordsmiths live to talk to him in person.

Hantengu's head is slashed by Muichiro and he splits into two clones. Muichiro is blown away by Karaku. Tanjiro, Nezuko and Genya are stunned when the clones split into more clones. Muichiro rescues Kotetsu from a Goldfish Demon.

Muichiro, with the help of air blown by Kotetsu to him, escapes Gyokko's Water Prison Pot. Muichiro finally recalls his tragic past.

Tanjiro, Nezuko, and Genya are struggling through an arduous battle against Zohakuten and his five tree dragons. They are forced to fight defensively against the tree dragons using the four emotion demon's powers, and Tanjiro is swallowed by one of them amidst the fight. Just as Tanjiro is close to meeting his demise, Mitsuri arrives in the nick of time and rescues him. And now, Mitsuri faces off against Zohakuten to rescue the captured Nezuko and Genya...!