.hack//SIGN

.hack//SIGN starts in a fictional 2005, introducing a computer virus called Pluto’s Kiss as the cause of a massive Internet shut down. The results are described as catastrophic: traffic lights shut down, planes collide in midair, and the United States’ nuclear missiles are nearly launched. As a consequence, cyberspace is subjected to severe restrictions. The virus affects all operating systems except for one, Altimit OS, the only operating system immune to all computer viruses.