Doraemon Movie 31: Shin Nobita to Tetsujin Heidan - Habatake Tenshi-tachi

Nobita's jealousy over Suneo's new robot sends him searching for something even more impressive. Mysterious giant parts begin falling from the sky, and with Doraemon's help he secretly assembles them into an enormous robot in the Mirror World, treating the machine like the ultimate new toy.

The truth is far more dangerous. A girl named Riruru arrives looking for the robot, revealing a connection to a mechanical civilization preparing to invade Earth and enslave humanity. Nobita, Doraemon, and their friends must decide how to stop an army vastly stronger than themselves, while their growing bond with Riruru complicates the line between enemy and ally.