Chiharu the cyborg and Makina the cyborg are arrested for violating the Galactic Road Traffic Act. At the same time, the police also arrest two other eccentric duos: Akane and Kanata the cyborgs, and Kurt and Max the cyborgs. Police officer Ryoko gathers them all together and assigns them a volunteer task: cleaning the interplanetary train known as the "Milky☆Subway." It was supposed to be a simple mission, but before long, they find themselves embroiled in a major incident.

(Source: Kadokawa, translated)