When an industrial robot named Monroe begins to work at his father's factory, Satoru is fascinated. As he and his friend Marin spend more time with Monroe, they start to suspect there's more to the machine than anyone else realizes. But neither children nor adults are prepared for Monroe's violent awakening into consciousness.

When Satoru is dragged off to Niigata and Marin to England, the robot Monroe is left alone at the factory. The abandoned Monroe then escapes, leaving all three friends to face the world without one another.