18 years ago. Oracle, a top-secret artificial brain, awakens its "personality" and tries to prevent its own extinction, causing a "breakdown". Public equipment and the Internet instantly came under Oracle's control. The "war between man and machine," which triggered the collapse of the human race, broke out. Washington, Moscow, and London... Famous metropolitan areas are "destroyed" and become debris within 24 hours of the incident. Unmanned weapons just cover the sky. The more troops a country has, the greater the damage. In Japan, which has a thin military production industry, the damage was still somewhat moderate.