Milky☆Subway: The Galactic Limited Express

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)