One day Doraemon, Nobita, Shizuka, Gian and Suneo were shooting a film as space heroes. When they were shooting the film in the open lot a boy called Aron comes and alerts them of aliens attacking his planet. They agree to help him by turning into real superheroes, but it isn't as easy as it looks.
When Nobita goes diving with Doraemon, a mermaid named Sophia comes close to him and they all befriend her. When they proceed towards her kingdom, they encounter a fight between two opposing tribes.
Nobita and Doraemon find a giant robot in pieces which they later assemble. It turns out to be a destructive weapon and the gang must save Earth from an imminent invasion.
Nobita and Doraemon use time tree Mochi and catch a big bird, which has been extinct for 500 years ago. To protect the animal, Nobita and Doraemon go to Beremon Island, overseen by a golden beetle named Herakles.
Nobita finds a stray dog and brings him home, little does hi knows that the dog is actually a prince in his homeland, a world appart deep in the african 'Smokers Forest' were the dogs evolved and have their own empire, so he and his friends take on a journey to take back the young prince to his homeland but when they get there things have changed.
While Nobita is sleeping, he suddenly feels the floor is trembling, like there would be an earthquake in his room. A little rabbit from an alternate universe named Chamii opens the door between the dimensions using a hammer and gets inside Nobita's room through the floor. Nobita wakes up and Doraemon hears somebody steal food from the fridge in the kitchen. It is Chamii, who gets caught by Doraemon and Nobita. She shows them the passageway through Nobita's floor into the spaceship. After they enter the spaceship, they see Koya Koya Planet. They meet a boy named Roppuru.
While Doraemon is asleep, a famous thief comes and steals his cat-bell. Without his cat-bell, Doraemon starts to act more and more like a normal cat. In order to stop this, Nobita, Shizuka, Suneo, and Gian have to go and search for his bell, so they go to a factory where all of Doraemon's gadgets are made.
