Nobita wonders what the world would be like if mirrors didn't exist, and he and Doraemon use the What-If Phone Booth to eliminate mirrors from the world. Both of them check out the changes after they made the call, and to their amusement, Tamako and Nobisuke are in for a shock when they groom their faces improperly. Going out the house, they are delighted to find all the mirrors disappear, and no reflection of them could be seen on the puddles of water and the windows. They find Dekisugi drawing portraits of two classmates at the park, who are offended when they see each other's faces for the first time. They go to Suneo instead, who had set up a portrait sketching booth outside his house for all the female classmates, including Shizuka.
Both of them later find Gian imagining what his face would look like at the open lot. Doraemon takes out a box gadget that has a reflecting glass inside (Doraemon's gadget is not affected as he himself witnessed the phone call) and ushers Gian to see it for himself. Gian sees someone in the glass that repeats his actions simultaneously, and is injured while fighting with him. He gets Suneo and Shizuka to see the glass for themselves, who all see their faces for the first time. Gian chases after Nobita and Doraemon when the former makes an insulting remark about his appearance, with Shizuka trying to stop him from catching the both of them. Meanwhile, Suneo admires his face on the glass. A passer-by sees someone that looks exactly like him on the glass while on his way home and takes the box to the police station.
The passer-by shows the box to the policeman, who are startled to find two men doing the exact same actions as themselves. Nobita and Doraemon see the policeman firing shots at the "multiplied" men in the glass and Doraemon flies back to the phone booth to revert the changes. The two men realize they are fighting against a mirror and are left puzzled. As Nobita and Doraemon run away from the two men, Nobita suggests using the phone booth to turn everyone's faces into Nobita's face. Soon after, everyone joins in the escape and become Nobita, including Doraemon himself!
In many overseas broadcasts, due to this episode lasting for only 11 minutes, the episode Nature Plastic Model Series was aired together to make up for the underrun.
