The story begins with the mysterious appearance of the word "Hi" on the wall of protagonist Aaron's home. As Aaron delves into the mystery, he encounters a series of horrifying events. Julia , an ancient book enthusiast, speculates that these occurrences are the result of a mental contagion or the " Free Virus " from the enigmatic country " Uni-Kingdom ." She temporarily names the manipulator of this mysterious force the " Wall God ." During his investigation, Aaron realizes he cannot recall his parents' names or faces, nor can he remember when his ten-year-old brother Louis started living with him. He even begins to doubt the existence of his brother. When Aaron seeks help from the police, the " Wall God " leaves a message on the police car window: Liar. Every choice Aaron makes brings him closer to uncovering the truth behind the " Wall God " and his own past. This novel seamlessly blends Asian horror and Western monster sci-fi, delivering plot twists that will surprise and engage readers. Clues scattered throughout the story invite readers to piece together the mystery, revealing that what we perceive may not always be the truth, and exploring the duality of human nature.