System Sfiyer is a world system that supports human life through advanced technology. As the system continues to upgrade, hackers and dangerous viruses also grow stronger. Elite fighters known as Ridder protect the system and maintain balance. Everything changes when a high-ranked virus appears in human form—a girl called S-02. As people begin to fall unconscious after encountering her, fear spreads. Is S-02 only a virus, or something that might change the future of System Sfiyer?