Nobita uses Doraemon's cloning gadget to make a clone of himself so that he could shop for clothes with Shizuka while the clone and Doraemon go to Suneo's house to play with him and Gian. To make the choice of clothes easier, Shizuka uses the gadget to create a clone of herself, but the clone becomes possessive and after a scuffle, the gadget ends up in Nobita's hands. Now Nobita needs to find out who the real Shizuka is by asking a question only she can answer.
