Shin-chan and his group create a box house and decorate it with flowers, animal pictures, and Shin-chan's action robot for a competition. Misae, Shin-chan, and Hiroshi segregate the unwanted things present in the house that can be sold in a flea market and find Shin-chan's baby toys. Misae, Keiko, and Shin-chan put up a stall to sell their things. Shin-chan barters his old toys for better ones.