Doraemon is sent back in time by Nobita Nobi's great-great grandson Sewashi to improve Nobita's circumstances so that his descendants may enjoy a better future. In the original time-line, Nobita experienced nothing but misery and misfortune manifested in the form of poor marks and grades, physical disasters, and bullying throughout his life. This culminates in the burning down of a future business he set up which leaves his family line beset with financial problems. In order to alter history and better the Nobi family's fortunes, Sewashi sent him a robot called Doraemon.

Nobita no Nejimaki City Boukenki est le 18e film de la série Doraemon. Lorsque Suneo se vante de posséder un ranch familial privé, Nobita et ses amis le forcent à le prouver en leur faisant visiter. Mais pendant la visite, Doraemon l'envoie lui et tous ses petits copains dans une incroyable ville-horlogerie où les jouets peuvent prendre vie.