Doraemon: Nobita and the Steel Troops

Nobita and Doraemon find a huge robot part fallen from the sky and hide it in the pond in the garden. When they put the pieces together, what stands there is a war machine many times their own size. Before long a girl called Riruru turns up looking for it; the planet she comes from is preparing an army to take the Earth. What Nobita builds with Riruru decides how the coming invasion can be stopped. It is among the best-loved and the darkest of the Doraemon features. The story opens like a toy adventure and goes on to war, enslavement and sacrifice, describing directly how the robots' own society was made. The decision taken at the end is unusually heavy for a children's film. The source is Fujiko F. Fujio's manga. It was remade in 2011, with parts of it changed in that version.