Ever since the death of his father, the burden of supporting the family has fallen upon Tanjiro Kamado's shoulders. One day, Tanjiro decides to go down to the local village to make a little money selling charcoal. On his way back, night falls, forcing Tanjiro to take shelter in the house of a strange man, who warns him of the existence of flesh-eating demons that lurk in the woods at night. When he finally arrives back home the next day, he is met with a horrifying sight - his whole family has been slaughtered. Worse still, the sole survivor is his sister Nezuko, who has been turned into a bloodthirsty demon. Consumed by rage and hatred, Tanjiro swears to avenge his family and stay by his only remaining sibling. Alongside the mysterious group calling themselves the Demon Slayer Corps, Tanjiro will do whatever it takes to slay the demons and protect the remnants of his beloved sister's humanity.

A mysterious string of disappearances on a certain train has caught the attention of the Demon Slayer Corps, and they have sent one of their best to exterminate what can only be a demon responsible. However, the plan to board the Mugen Train is delayed by a lesser demon who is terrorizing the mechanics and targeting a kind, elderly woman and her granddaughter. Kyoujurou Rengoku, the Flame Hashira, must eliminate the threat before boarding the train. Sent to assist the Hashira, Tanjiro Kamado, Inosuke Hashira, and Zenitsu Agatsuma enter the train prepared to fight. But their monstrous target already has a devious plan in store for them and the two hundred passengers: by delving deep into their consciousness, the demon intends to obliterate everyone in a stunning display of the power held by the Twelve Kizuki.

The devastation of the Mugen Train incident still weighs heavily on the members of the Demon Slayer Corps. Despite being given time to recover, life must go on, as the wicked never sleep: a vicious demon is terrorizing the alluring women of the Yoshiwara Entertainment District. The Sound Hashira, Tengen Uzui, and his three wives are on the case. However, when he soon loses contact with his spouses, Tengen fears the worst and enlists the help of Tanjiro Kamado, Zenitsu Agatsuma, and Inosuke Hashibira to infiltrate the district's most prominent houses and locate the depraved Upper Rank Demon.

For centuries, the Demon Slayer Corps has sacredly kept the location of Swordsmith Village a secret. As the village of the greatest forgers, it provides Demon Slayers with the finest weapons, which allow them to fight night-crawling fiends and ensure the safety of humans. After his sword was chipped and deemed useless, Tanjiro Kamado, along with his precious little sister Nezuko, is escorted to the village to receive a new one. Meanwhile, the death of an Upper Rank Demon disturbs the idle order in the demon world. As Tanjiro becomes acquainted with Mist Hashira Muichirou Tokitou and Love Hashira Mitsuri Kanroji, ferocious powers creep from the shadows and threaten to shatter the Demon Slayers' greatest line of defense.

After a series of mighty clashes with Upper Rank Demons, the Ubuyashiki clan prepares for one last battle with the hellish forces of Muzan Kibutsuji. In order to finally defeat the Demon leader once and for all, the clan devises a training camp for the Demon Slayer Corps, one led by the remaining Hashira - the most elite warriors in the organization. Each Hashira forms a specialized exercise that will hone both their own abilities and the skills of the ordinary soldiers. Tanjiro Kamado, a boy at the heart of the brewing conflict, recovers from wounds received in a recent fight. While his half-Demon sister Nezuko is studied by researchers like Shinobu Kochou, Tanjiro embarks to train with the Hashira, seeking mastery in each of their assigned areas of expertise to be best prepared for the coming war - skills vital to Tanjiro, as he has vowed to be the very warrior who will eliminate Muzan for good.