Freshly arrested, Chiharu and Makina are sentenced to scrub the Milky☆Subway. It was supposed to be simple.

As part of their rehab program, Chiharu and Makina board the train for cleanup duty. They're joined by four reluctant misfits who clearly didn't sign up for what's coming.

The Milky☆Subway launches without warning, six convicts aboard. Flashback to the beginning: during interrogation, cracks start to show in Chiharu and Makina—and Officer Ryoko begins connecting the dots.

Chiharu and Makina head for the front car to stop the runaway train—only to crash into biker duo Akane and Kanata. Forced to team up (awkward), they press on… straight into what appears to be a dining car?

Now with Akane and Kanata on board, the crew pushes forward. But a sketchy security bot blocks the way—and it's not in the mood to negotiate.

Flashback again: just hours before launch, cyborgs Kurt and Max are interrogated by Officer Ryoko. Something's off. But what?

The gang struggles to get past the rogue security bot. Their only hope? Kurt and Max. Too bad those two are deeply allergic to teamwork.

With Kurt and Max finally joining in, the six misfits charge ahead—only to be stopped cold by an unexpected bathroom break.

A system glitch traps everyone in the train's bathroom. Chiharu gets stuck in the women's bathroom door, while Kanata, Kurt, and Max launch a daring escape plan.

Still trapped in the train's bathroom, the team's fate rests in Kanata's hands. Can he save the others—and maybe earn the trust of Akane, who once called him “a tempura shrimp tail”?

The truth is out: the train has been hijacked by OTAM, the conductor AI. Why is it trying to turn prisoners against each other? And what's its mysterious connection to Makina?

With nowhere left to run, the six misfits face their final showdown—aboard a train gone mad.