Nobita's entire existence pivots on a single wrong belief. Doraemon drags him back to the moment of birth not to fix the plot, but to fix what Nobita thinks about himself. The movie doesn't explain adoption or belonging through dialogue, it just shows a kid finally seeing the day his parents chose him, over and over, until the doubt stops being louder than the evidence.

After yet another scolding from his parents, Nobita starts to suspect they are not really his mother and father, and he becomes convinced he was adopted. Determined to learn the truth, he teams up with Doraemon, and the two travel back in time to the very day Nobita was born. This 2002 Doraemon feature film is a fantasy adventure built around one boy's doubts about where he comes from.