Yūko Okonogi (nicknamed Yasako) and her younger sister Kyōko arrive by train to Daikoku City. Their virtual pet dog Densuke goes missing when he falls into an abandoned zone of cyberspace occupied by an illegal. Yasako enlists the aid of Fumie Hashimoto, a detective from the Coil Cyberinvestigation Agency, to help rescue her pet. In their efforts, they attract the attention of Searchmaton.