Spike Spiegel, a bounty Hunter with a dark past, lives on bounty to bounty, barely making it each time, or not making it at all. His partners Jet Black, Faye Valentine, Ed and Ein the dog all help him in his adventures from planet to planet.
In a far distant future, humanity has embraced the Fractale system as the ultimate path towards utopia. Comprised of several trillion networked computers, Fractale was created in the 22nd century to promote a peaceful lifestyle for the entire world in exchange of a periodic recovery of personal data from individuals through terminals located within their bodies. Living in a rocky coast region, Clain is a young boy fascinated by old technology. After helping a girl named Phryne, she gives him a pendant before disappearing by the next morning. Accessing the data from the peculiar gift, Clain ends up summoning a girl-shaped avatar named Nessa. Together they start a journey as they discover the truth behind the Fractale system.
Junpei Kōsaka is a second-year high school student who despises cats and has an allergy to them. It just so happens that his high school crush is Kaede Mizuno, a girl who adores cats. One day, while walking home from school, Junpei kicks an empty can and unfortunately beans the local neko-jizō-sama (guardian deity of cats). Soon, he finds he can now understand what cats are saying, including his family's own ill-tempered cat, Nyamusasu. However, if he does not grant 100 wishes from cats, he will turn into a cat himself.