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.