Doraemon's Long Day (ドラえもんの長い一日 Doraemon no nagai tsuitachi) is an episode from the Doraemon 2005 anime.
Nobita is preparing a gift on Doraemon's birthday, but in an accident damages a premium dorayaki Doraemon has bought earlier. Nobita drops a bombshell by accidentally blurting out that Doraemon is a useless robot. In a fit of anger, Doraemon leaves with Dorami for the future. But when he learns that he is going for a medical checkup, he attempts to get away with it by switching bodies with Dorami, but fails. During the medical checkup, a wanted criminal, Denja, is brought into the hospital after he robbed a bank and gets into a car accident. He sees the Substitution Rope that has been exposed from Doraemon's pocket when he visited the hospital, and switches bodies with Doraemon. Denja, in Doraemon's likeness, goes to the 21st century to go after Nobita, while Doraemon, in Denja's body, is framed for committing the crimes made by the latter and tries to escape from being arrested by the police and Time Patrol. Can Doraemon go back to the 21st century and get his body back? And can Nobita identify who the real Doraemon is?