The group was founded by Ai (who goes by the names Jai, Lai, and Kai in Extras to keep anonymous), but the official leader is whoever has the lowest face rank at any one time. Except for Eden Maru, they all have generic bodies and faces designed to disappear in a crowd. Although each girl is anonymous, the group in general is legendary due to their incredible, often dangerous tricks including bridge-jumping and mag-lev surfing. Their name soon became synonymous with mysterious forces in the world, like pixies. There are twelve members of the Sly Girls, including Ai, Eden Maru, Miki, and Pana.
Eden, a skilled hoverball player and the Sly Girls most famous member with a face rank around 10,000, is followed to a Sly Girls meeting by Aya Fuse and her beloved hovercam, Moggle. Aya had spotted her earlier with the secret clique as they surfed mag-levs and wants to kick the story first, which would undoubtedly catapult her into mega-fame. However, Aya doesn't expect Eden to have realized that she's being followed and before she knows it, Aya is ambushed by the Sly Girls. They dump her in the lake of the underground storm-drain that they're hiding in, telling her that they don't like kickers.
Not wanting to get dunked in the cold water again, Aya thinks fast and claims she's not there to kick a story, she wants to join them. Impressed that the fifteen-year-old is brave enough to have followed them at all, their leader, Jai, allows her to join... if she lets them drop a locked-down Moggle into the dark depths of the underground lake. Tearfully, Aya allows her only friend to sink to the bottom. They don't let her surf with them right away, however. They want to see if she's truth-slanting about being a kicker, and so send her home instead, saying that they'll be in touch.
The next night, they invite Aya to surf a mag-lev with them. Jai explains that if anyone in front of her waves a yellow light, it means duck. If the light is red, it means a tunnel is coming and she must lie flat on the train. They wait on a rooftop until the train hits a bend in the track and slows down to just a hundred and fifty kilometers before they activate their special hoverboards, which have been programmed to fly themselves until they match the train's speed. The girls then maneuver close to the train and carefully attach their heavy-duty crash bracelets to magnetize to its metal body. They slide the bracelets from their wrists to their ankles, rooting them firmly to the mag-lev while simultaneously allowing them to stand up and truly "surf" on top of the three-hundred-kilometers-per-hour train.
This time though, the mag-lev unexpectedly stops inside the tunnel. Aya and another Sly Girl, Miki, witness strange creatures with frightening, alien bodies open up the smart matter tunnel wall to reveal a cavern filled with wall-screens, food synthesizers, and even a fish tank. The strange beings exchange these things with massive metal cylinders. Eventually, the train gets moving again and the Sly Girls jump off. When Miki and Aya report what they've seen, Jai decides to use a very-illegal matter-hacker to break into the smart matter wall to find out what's going on.
Once inside, the Girls immediately have fun exploring the huge space within, filled with dusty equipment and the strange metal cylinders they saw the alien-like creatures bring in. But before too long, the shadows start playing tricks on them and they begin to grow uneasy. Miki even thinks she sees something following her and Aya, and runs back to get the other Girls.
Aya discovers with relief that its only Moggle, whom she's rescued and coated in black camo paint so he can better spy on the Sly Girls without their knowledge. She orders her little hovercam to hide, so it does, inadvertently leading the Sly Girls to an airlock chamber. As they wait for Eden to explore it, Aya secretly uses her eyescreen to look through Moggle's point of view and sees that he's found a way outside at the top of the mountain, with a perfect view of an unscheduled mag-lev headed straight for them.
Jai, now called Kai, had left the secret door wide open, and Aya knows that the powerful wake of the train could suck everything not tied down, including their boards, into its slipstream. The Sly Girls don't really believe her - how could she know a train is coming? - but the risk is too great to ignore. As they get close to the open door, they can unmistakably feel the train rumbling on its way. Eden frantically tries to close the door, managing to work the matter-hacker's controls just in time.
The danger passed, the exhausted Girls are ready to call it a night, but not before swiping a few things like wall-screens and workstations from the disorganized jumble of equipment. Aya realizes that without face ranks or merits (which Kai hates even more than fame), the Girls can't do much requisitioning. Stuffing Moggle into a random storage-container, Aya is ready to go home.
Soon after, Aya becomes famous as the Slime Queen. After rescuing Moggle from the storm drain, covered in muck, she had been greeted by the famous Frizz and the paparazzi cameras following him. After much argument, Kai grudgingly agrees that Aya's sudden burst of fame is not entirely her fault, but bans her from the Sly Girls until her face rank drops once again to six figures.
- The only Sly Girl to mention her face rank is Miki, who is around 997,000, although Jai mentions that her face-rank climbed almost above 999,000.
- Aya, at fifteen years old, appears to be be the youngest of the Sly Girls.