The Great Escape from the "Thank You Very Much" Prison

Nobita hasn’t finished his summer vacation homework by the time school reopens. Doraemon scolds Nobita for being lazy again, but Nobita doesn’t listen, and the latter proceeds to take out the What-If Phone Booth from the spare pocket and creates an alternate reality where scolding should be avoided.

Nobita becomes very happy in this reality where others can't get angry when he doesn't do his homework or leave side dishes that he doesn't like. Disappointed with Nobita, Doraemon goes to the future to catch up with Dorami. To his surprise, he learns that scolding had been outlawed and anyone caught scolding would be arrested. Doraemon decides to return and reverse the change as Dorami leaves him, but when he is involved in an altercation with three boys playing hoverboards, their robot teacher, Ikkoku, punishes one of them, and both Doraemon and Ikkoku are arrested and taken to prison.

At school, the teacher doesn’t punish Nobita for forgetting to finish his homework, though Shizuka thinks it is a bad idea to let it pass. In the offshore island prison, run by the diamond-obsessed Majime (whose forefather is a journalist in the present day) and superintendent Donpa, and guarded by ant robots, Doraemon and Ikkoku meet other prisoners, Gonsuke, who has just been arrested for arguing with someone who wasted food, Jiji, an elderly robot who does best at preaching, and Garakuta, who was arrested for arguing with someone who doesn’t treasure his items. Majime goes back in time to steal the What-If Phone Booth. Doraemon and the inmates are sent to forced labor, where it is revealed that the prison is also a diamond mine.

Back in the present, Nobita and the others break one of Kaminari’s bonsai plants, but the latter doesn’t get mad. Nobita returns home feeling bad about himself. He sees Majime stealing the phone booth and tries to ask if he is related to Doraemon, but when he responds to his friends when they arrive to celebrate Doraemon’s birthday, Majime and the phone booth disappear.

Dorami finds Doraemon missing and goes to the present to get Nobita and friends’ help to find him. They meet one of the boys from earlier, Ganta, and take him to Dorami's house to console him. Ganta feels guilty for Ikkoku, who tried so hard not to lose his temper and go to jail as a result, and hopes to seek forgiveness from him. Nobita promises Ganta that they rescue Doraemon and Ikkoku. Dorami and the others try to investigate the prison but to no avail. Nobita uses Doraemon's spare 4D Pocket, which is connected to the original 4D Pocket, and goes inside without them knowing for fear of putting them into danger.

Doraemon and his fellow inmates embark on their prison break. They attempt to escape through the staircase and the diamond mine, fending off ant guards and guard dogs along the way. Nobita ends up in the prison control room where Donpa works and makes his way out without being discovered. He then tries to find a gadget to rescue Doraemon. Doraemon and the others are cornered by the ant guards and begin to succumb to their fate, but Nobita then arrives and subdues all the guards.

Nobita returns Doraemon his 4D pocket that was confiscated when he entered the prison, allowing him to use his gadgets to help him and his fellow inmates break out of the prison, using the Genius Helmet and Technical Gloves to remodel the iron ball that was attached to him and defeat Donpa. Doraemon and the others finally reach the prison yard, but Majime starts to control the giant statue in the prison yard and attempts to squash Doraemon and Nobita.

Dorami and the others arrive to help them deal with Majime, while Ganta finally reconciles with Ikkoku. Jiji and Garakuta proceed to free the other prisoners as Majime goes on to battle against Doraemon and Nobita. As Doraemon is about to fall to his death, Nobita messes up Majime’s hair causing him to seeing with anger, but is then quickly subdued. With Majime beaten, Nobita proceeds to restore things back to normal but before doing so Manjime ask if he was sure about it and he answered yes because he learned the reason for scolding it’s because that they care about them Nobita and Doraemon return to the very same day the former used the phone booth as to celebrate Doraemon’s birthday.