The year is 2027 in Mega-Tokyo, six years before the Knight Sabers will make their debut. Boomers — androids that look, think, and act almost like human beings — are still a relatively new technology, and the implementation and integration of boomers into society is still a bit buggy — sometimes fatally so. Whenever a boomer incident occurs, though, there is the Advanced Police, a special force trained to deal with boomer crimes.
Leon McNichol is a rookie in the AD Police, just starting to become exposed to the horrors and tragedies one is confronted with in everyday Mega-Tokyo. He and his veteran partner, Gina Marceau, slowly learn about the ever-fading line that separates man from machine.