Nobita has had some bad luck recently. he was reprimanded by the teacher at school for his homework, ridiculed by his friends for his poor baseball skills, and scolded by his mother for his messy room. Sad, he is whimsical, hoping that some kind of magic can help him take care of it. With the help of Doraemon's "what if phone booth", their world has become a magical world, unfortunately Nobita is still the worst one. At the same time, the mysterious celestial bodies are approaching the earth, and Demao, the king of the demon world, tries to rule the world. He predicts that Nobita and his friends will stand in his way, so he sends the witch Medusa to root out these stumbling blocks. Nobita, they are in an unprecedented crisis.