In 3022, the third year after the "Code Calamity" began, 90 percent of life on Earth has been infected and mutated by seven types of "code," each aligned with an element such as fire, earth, or water. Cities have become ruins, and humanity struggles to survive on the brink of extinction.
Lin Ye, a survivor from the lowest rungs of society, is searching for his younger sister, Lin Xi, who disappeared three years ago after being infected by Fire Code. When he is nearly killed by the Earth Code creature known as the Rockshell Beast, he awakens the legendary "Attribute-less Return Art," which lets him reduce any code energy to zero through sheer will. This power puts him in grave danger: the official organization, the Keepers of Order, sees him as a heretic and wants to capture him for study, while the underground organization, the Code Rebels, wants to recruit him to fight the Keepers.
Working with Su Ran, a Fire Code prodigy from the Keepers, Lin Ye accidentally discovers that the remains of every code he has reduced to zero contain coordinates pointing to the "Code Mother Nest" on the far side of the moon. It is an experimental device built by a higher civilization, and the Return Art is a "countermeasure program" embedded in human genes. The truth is even crueler: he is the seventh Zeroer. The first six all perished from the backlash of their powers, and the only reason he has been able to stave off code infection is a "Fire Code fragment" left behind by his sister.
To end the Code Calamity, Lin Ye joins Su Ran and Night Owl, leader of the Code Rebels, and transmigrates through deadly places such as the Fire Code volcanic belt and the Water Code deep-sea base to collect the "Return Cores" of the first six Zeroers. He not only reunites with his sister, who has become symbiotic with Fire Code, but also realizes that the true purpose of the Return Art is "repair."
In the final battle, Lin Ye rejects the choices to "erase his memories" or "lose the Return Art." Using himself as an "anchor," he rewrites the program, allowing code and humanity to coexist. Earth enters the "Era of Symbiosis," and Lin Ye becomes the "First Zeroer." Alongside his companions, he deals with "symbiotic anomalies" and prepares for the return of the higher civilization.
