The game is set in the future. Tokyo, Japan's capital, was destroyed in a nuclear explosion early in the 21th century, but some years later, the Tokyo of the nineties was digitally recreated. People now live in a virtual world, and everything is ruled by computer programs. But some programs don't work correctly, and one day, a pop concert is disrupted by a terrible demonic vision. A special agency recruits the hero of the game, Kei (which can be either female or male, depending on your choice), to travel through the virtual world and to confront and stop the hackers.