Takeshi Hongo is a promising young man with a passion for motorcycle racing. However, his dreams are suddenly ruined when he gets kidnapped by Shocker, the evil secret organization planning to dominate the world. After being remodeled into a cyborg, Takeshi escapes and swears to protect the world from the inhuman monsters.

When a sickly young girl suddenly becomes obsessed with inventing new things, her family and friends are all puzzled. "What has gotten into Myne?" they wondered, never dreaming that the answer is not a "What" but a "Who": Urano Motosu, a book-loving apprentice librarian who died in an earthquake in Tokyo who somehow found herself in Myne's body! And since Myne's world is still in a medieval stage, where books can only be owned by the elite, the new Myne intends to do everything she can to bring her beloved books to the masses in the time she has left.

After a demon attack leaves his family slain and his sister cursed, Tanjiro embarks upon a perilous journey to find a cure and avenge those he's lost.

Tanjiro and Nezuko have been apprehended by the Demon Slayer Hashira, a group of extremely skilled swordfighters. Tanjiro undergoes trial for violating the Demon Slayer code, specifically smuggling Nezuko, a Demon, onto Mt. Natagumo. A recap of Kimetsu no Yaiba episodes 22–26, with new footage and special end credits.