The story begins with Nobita and Shizuka sitting on the pipes in the yard they hang out at while Suneo showed off his robot. Nobita grew jealous and asked Doraemon to build him a giant robot.

Because the monkey king is only a legend, Nobita and Doraemon have decided to go back in time using the time machine and make a fake one and show Gian, Shizuka, and Suneo to prove that they are right.