PERSONAL DEMON Shin looks like an ordinary high school boy, but he has a terrible secret- an alien parasite has infected his body. This mysterious creature is ruthless, deadly, and utterly indifferent to human suffering . . . and it is beginning to assert itself over Shin. As Shin fights for control of his body, can he also hold on to his humanity?

An ordinary teenage boy named Shinichi Izumilives with his parents in a quiet neighborhood until alien parasites invade. They are worm-like creatures that enter human 'hosts' through their ears or noses, and take over their brains. A Parasite attempts to crawl into Shinichi's ear and take over his brain while he sleeps, but is stopped by his headphones and accidentally burrows into one of his hands instead. With separate intellects, he and his parasite, Migi, fight the invasion of the town.