It is the Correct Century, two millennia after a devastating conflict which left the world broken. Earth is now mostly uninhabitable, and thus a remnant of humanity has resided on the Moon while the Earth and its few survivors recover. For years, the Moonrace, the people of the Moon, have continued to check if Earth is fit for resettlement. A boy named Loran Cehack and two others are sent down to Earth for a reconnaissance mission. Loran ends up spending a year on the planet working for the Heim Family, aristocrats living in a Victorian-like society. This family, like others of similar wealthy status, celebrates one's coming of age with a ceremony involving a giant stone statue known as the White Doll. To Loran's surprise, the Moonrace suddenly touches down on Earth with the intent of taking it by force. During the attack, the White Doll is broken apart, revealing a mobile suit called the Turn A Gundam inside. With Loran in its cockpit, the Turn A causes a standoff between the forces of Earth and Moon. The young pilot, along with the people of both sides, must keep the peace and avoid another all-out, catastrophic war.

Romeo is a kindhearted and courageous boy living with his family in a small village in Switzerland. Unfortunately, Romeo becomes the interest of a man named Luini, known as The God of Death, who is infamous for buying children and selling them as chimney sweeps in Milan. While visiting the village, Luini burns down Romeo's family cornfield in an attempt to have Romeo as his own. With the cornfield gone and his father sustaining a head injury trying to put out the fire, Romeo bravely sells himself to the God of Death in order to help his family afford a doctor. On his way to Milan, Romeo meets a boy named Alfredo Martini and they quickly become friends. Just as Alfredo is sold to a different master, the two boys swear eternal friendship and vow to meet again. As a chimney sweep, Romeo faces many hardships and abuse, especially from his master's family and a gang known as the Wolf Pack. But after reuniting with Alfredo, the two form a fraternity of chimney sweeps called The Black Brothers, who will learn to fight against the Wolf Pack and help each other in times of need.

Conan was the only child born on Remnant Island, a place settled by a group of refugees while they fled a terrifying wave of magnetic bombs that wiped out most of humanity. After 20 years, most of the castaways have died, save for Conan and the wise old man that raised him. Believing Remnant Island to be the last inhabited place on Earth, Conan is shocked when he discovers a young girl named Lana washed up on the beach one day. Though he is thrilled to learn that humanity has survived, Lana tells him the nation of Industria wants her as a hostage to force her grandfather, Dr. Lao, to power their machinery. Their conversation is cut short when Industria's top pilot, Monsley, suddenly appears and seizes Lana. Determined to save her, Conan immediately sets off from Remnant Island and begins a journey that will ultimately determine the fate of the world.

Famous writers throughout history find themselves being reincarnated by a mysterious, unseen entity known as the Alchemist. With their souls confined and bound to an expansive library, they are tasked by the Alchemist to jump into books to purify the pages of monsters called Taints. Along the way, they must also rescue and recruit fellow authors trapped within the very stories they themselves had written. Although the writers take on new and powerful forms for this endeavor, some still maintain a semblance of who they once were, while others struggle to remember their pasts and the works they had penned. Despite there being no apparent end to their grand mission, they remain committed to the cause in hope of resolving the mystery behind their collective resurrection as well as questions that have haunted their former lives.