The protagonist, Kageyama, a programmer working on an AI system, is suddenly transported to a white void during a holiday crunch. There, he encounters an enigmatic, androgynous being who claims Kageyama's world is a simulation, and the being is its "owner" or "simulator." This entity, not a Homo sapiens, explains that the world is a simulation akin to a popular game, with its scale encompassing 14 galaxies. The simulation is abstracted to save computational resources, only rendering details when observed.
The crisis arises because humanity's neural networks, particularly their brains, are consuming an exponential amount of processing power, far exceeding the simulator's expectations. The simulator, who refers to itself as a "game master" and whose actions are governed by "mana" (which decreases when simulated beings express dissatisfaction), cannot directly intervene without penalty. Instead, Kageyama is chosen as an "agent" to fix this "bug." He is granted the ability to manipulate the parameters of objects within the simulation, akin to editing a computer's registry, which he dubs "RegEdit." His primary task is to reduce Earth's population by approximately 4 billion people.
Initially overwhelmed and disbelieving, Kageyama's skepticism is shattered when he discovers he can indeed manipulate objects, transforming a mundane mug into gold. This ability, however, comes with physical side effects, including impaired motor functions. He also learns that his "RegEdit" ability is stored in his cerebellum, requiring temporary suspension of motor control functions to operate.
Kageyama uses his newfound power to generate wealth by creating gold objects and selling them, while also attempting to win the lottery by altering probabilities. This attracts unwanted attention, leading to him being perceived as a genius programmer who created a miraculous horse racing prediction system. To escape potential danger and scrutiny, he accepts a seemingly unrelated overseas assignment to Nigeria, facilitated by his colleague Ichikawa, who also happens to be transferred there.
In Nigeria, Kageyama is tasked with setting up cryptocurrency mining operations for his company. He encounters a bright, multilingual medical student named Lucas and his sister Charlotte, who are in dire financial straits after their father's business was taken over and their home lost. Kageyama, seeing an opportunity to fulfill his population reduction mandate and perhaps help them, invites them to dinner. He then orchestrates a staged accident where Lucas, acting as a fake victim, causes a commotion. This allows Kageyama to avoid paying the fake accident claim while subtly creating a situation that leads to violence among local criminal elements, indirectly causing casualties. He rationalizes this as a necessary step towards his mission, though he acknowledges the danger and complexity of his actions. Meanwhile, Ichikawa, who seems to have a complex relationship with Kageyama and a hidden agenda, is also present in Nigeria, suggesting a deeper connection to his predicament.
