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.

Moritaka Mashiro and Akito Takagi are pretty much foils of each other. Mashiro, an average 9th grade student but talented artist, and Takagi, an overall advanced 9th grader and aspiring writer. After great convincing, Takagi convinces Mashiro to join him in becoming the greatest mangakas Japan has ever seen. Takagi, with his gift of writing, hopes to become a successful mangaka, and Mashiro, with his gift of art, hopes to marry the girl of his dreams, Azuki Miho.

Kakeru, a former elite runner at high school, is chased for stealing food. He is saved by Kansei University student Haiji, who is also a runner. Haiji persuades Kakeru to live in the old apartment "Chikuseisou" where he plans to team up with fellow residents to enter Hakone Ekiden Marathon, one of the most prominent university races in Japan. Kakeru soon finds out that all of the residents except for Haiji and himself are complete novices.

Tanjiro Kamado, joined with Inosuke Hashibira, a boy raised by boars who wears a boar's head, and Zenitsu Agatsuma, a scared boy who reveals his true power when he sleeps, boards the Infinity Train on a new mission with the Fire Hashira, Kyojuro Rengoku, to defeat a demon who has been tormenting the people and killing the demon slayers who oppose it!

Yuta Okkotsu is a nervous high school student who is suffering from a serious problem—his childhood friend Rika has turned into a curse and won't leave him alone. Since Rika is no ordinary curse, his plight is noticed by Satoru Gojo, a teacher at Jujutsu High, a school where fledgling exorcists learn how to combat curses. Gojo convinces Yuta to enroll, but can he learn enough in time to confront the curse that haunts him?