Super human Chiharu and cyborg Makina are arrested for violating space traffic laws. They end up in a detention center alongside two other pairs of misfits: the super human duo Akane and Kanata, and the cyborg friends Kurt and Max. Police officer Ryoko sentences all six to one week of community service cleaning the interplanetary limited express train known as the Milky Subway. The task seems straightforward until a malfunction causes the train to suddenly launch into deep space with the inmates still on board. With no controls, no plan, and no clear destination, the group must scramble to survive the chaos inside the runaway train while navigating their own personal conflicts, grudges, and awkward bonds. Along the way they encounter a malfunctioning robotic attendant, a security robot that mistakes them for intruders, and urban legends about the train's cursed past. As they work their way toward the front car in search of a lost control key, past flashbacks reveal how each pair ended up arrested and why their relationships are so strained. The film is an expanded version of the twelve‑episode animated series, with additional scenes added after the end credits that offer a glimpse into what happens next.