Urano Motosu loves books and has an endless desire to read literature, no matter the subject. She almost fulfills her dream job of becoming a librarian before her life is ended in an accident. As she draws her last breath, she wishes to be able to read more books in her next life. As if fate was listening to her prayer, she wakes up reincarnated as Myne—a frail five-year-old girl living in a medieval era. What immediately comes to her mind is her passion. She tries to find something to read, only to become frustrated by the lack of books at her disposal. Without the printing press, books have to be written and copied by hand, making them very expensive; as such, only a few nobles can afford them—but this won't stop Myne. She will prove that her will to read is unbreakable, and if there are no books around, she will make them herself! [Written by MAL Rewrite]

Now branded for death and destined to be hunted by demons until the day he dies, Guts embarks on a journey to defy such a gruesome fate, as waves of beasts relentlessly pursue him. Steeling his resolve, he takes up the monstrous blade Dragonslayer and vows to exact vengeance on the one responsible, hunting down the very man he once looked up to and considered a friend. Along the way, he encounters some unlikely allies, such as a small elf named Puck, and Isidro, a young thief looking to learn swordsmanship from the former mercenary. As the ra group slowly comes together after having decided to join Guts in his quest, they will face incredible danger unlike anything they have ever experienced before. [Written by MAL Rewrite]

Demons have now become commonplace around the kingdom of Midland, which has fallen into chaos. The swordsman Guts still cannot stay in one place for long due to his demonic brand. He could always manage to protect himself when he was alone, but now he has the added challenge of protecting former Commander Casca, a shell of her former self who neither remembers nor trusts him. They never have a moment's rest with the constant threat of demons, and they need a place where Casca will be safe till they find a way to heal her. Their elf ally, Puck, tells of the mystical land of Elfhelm, which is supposed to be a safe haven from the demons that ravage the lands. Tired and with only a vague hope, they struggle on to find a place to live—and they still need to find those responsible for the madness they are forced to endure. [Written by MAL Rewrite]

Following the conclusion of the three-way organizational war, government bureaucrat Ango Sakaguchi recalls an event that transpired years ago, after the death of the former Port Mafia boss. Osamu Dazai, still a new recruit at the time, was tasked with investigating rumors related to a mysterious explosion that decimated part of the city years ago—and its connection to the alleged reappearance of the former boss. Due to circumstances out of his control, he is partnered with Chuuya Nakahara, the gifted yet impulsive leader of a rival clan known as the ''Sheep,'' to uncover the truth behind the case and shine a light on the myth of Arahabaki—the god of fire who might just lead Dazai to the case's solution. Meanwhile, in the present day, it is business as usual once again for the Armed Detective Agency. Their peaceful break will not last for long, however, as enemies old and new gather their strength and prepare for another face-off. [Written by MAL Rewrite]