From the introduction: The year is 2006 A.D., and our stage is set in Japan. Seven years ago, a meteorite collided with the Shibuya District of Tokyo, killing several people and introducing a hostile alien species call the Worm to planet Earth. After their initial attacks, they absorbed the memories and forms of their victims and blended in with the population before continuing their bloody campaigns on others. The organization ZECT was formed for the purpose of combating the Worm, though not all is as it seems...