Operation - Propose is the twelfth chapter of Doraemon Manga.
The chapter starts in the day of 12th anniversary of Tamako Nobi and Nobisuke Nobi. Nobisuke comes back home early for the party. Nobita asks both who proposed first, but both are arguing and fighting later. Doraemon uses Lie Detector but none are lying, so he and Nobita uses Time Machine to see their parents in 12 years ago.
At the past Tamako was waiting for Nobisuke for a long time because he was late due to the watch given by her. She ran away and go with another person with the same outfit because she mistaked. She noticed and run away. On the other hand, Nobisuke had another cute girl. Finally, both were mad. Doraemon used the Imitation Dummy to imitate both to make them propose each other. (This is the reason why the lie detrctor is not work on both.)
Nobita and Doreaemon goes back to the present. Both are finding their parents but they are not in home. Finally both forgives each other and see the moon.