In the cyber city Tom Sawyer, society revolves around earning "Love," akin to receiving likes on social media. Citizens of this augmented reality exchange Love for public services and appearance-changing avatars via the Decoration Customizer, also known as "Deco," a hologram device implanted in an individual's eyes from early childhood. Under the government's careful management, the people of Tom Sawyer live a peaceful existence, outside the occasional appearance of Phantom Zero, a mysterious criminal who brings all Love to zero within their vicinity.

Berry, a mischievous girl fascinated by Phantom Zero, lives comfortably in the system of Tom Sawyer until her Deco malfunctions, enabling her to see a camouflaged prankster named Hack. Believing Hack to be Phantom Zero, Berry chases after the suspect and, in the process, begins to uncover society's most well-kept secrets. As it turns out, Hack is not the only person living outside the system's rules—and the vibrant colors of Tom Sawyer hide a darker nature.