I'm Mari-chan

Learning that teen idol Mari Marui is having a shoot at a nearby park, Doraemon (who is an avid fan) and Nobita go there to catch her in action along with Gian, Suneo and Shizuka, but she is nowhere to be found. Later, Doraemon and Nobita find her hiding in one of the pipes at the Open Lot and invite her home. Mari, who is tired of her daily routine arranged by her manager-mother, wishes to take a break, so she switches places with Nobita using the Substitution Bar.

Nobita, as Mari, and Doraemon go out of the house and she reveals to Gian and Suneo that she is actually Nobita. They escape from the mob that follows them and back in a minibus for a magazine interview. Knowing that Nobita would not be the right fit for Mari's interview, Doraemon switch places with Nobita so the former becomes Mari instead, and they continue the interview successfully. Afterwards, they proceed to the television station to film a music segment of a programme, but "Mari" is too enthusiastic and is demanded by Mrs. Marui to lip-synch to the song.

After filming the segment "Doraemon" and "Mari" plan to call it a day, but Mrs. Marui forces "Mari" to continue her planned itinerary. Tired to continue midway through the busy schedule, "Mari" and "Doraemon" switch places with Mrs. Marui. Doraemon gets his body back, Nobita finds himself in the body of Mrs. Marui and the manager-mother herself of course continues the rest of the itinerary as Mari.

Doraemon and "Mrs. Marui" go home and invite "Nobita" for dinner with Mom too. After having dinner, "Nobita" decides to go and switch his body back. So they proceed to find "Mari", who is sitting alone at the park. Having understood what it's like to be tied down with work, "Mari" goes to apologize with "Mrs. Marui" and along with "Nobita" they switch their bodies back. Mrs. Marui walks back home with Mari promising not to give her too much work again. But Doraemon forgets to get Mari's autograph.