Nobita fantasizes about the prospect of playing the prince in an upcoming school play, opposite Shizuka. However, due to him daydreaming in class, that role had already been given to Dekisugi. He decides to vie with the other male classmates for the next-best role in the play, the King, through a rock-paper-scissors game, but loses the role to Gian and ends up playing the prey that the King shoots down.
Nobita returns home, finds a throne in the middle of his room and sits on it. He orders Doraemon to get him an ice cream and Mom to buy the groceries herself. Learning about the powers associated with sitting on the throne, Nobita summons Doraemon to get him another ice cream. He leaves the throne to receive the script of the play from the teacher before restoring himself to the throne and ordering him out.
Nobita orders Gian and Suneo inside the house and along with Doraemon, take him to the ice cream shop; and along the way he orders the commoners to bow down to him and police officers to escort him to his destination. He steals the role of the King that was offered to Gian before continuing the motorcade to Shizuka's house so as to rehearse the play with her.
But Nobita begins to get a stomachache from having too much ice cream and dethrones himself in the middle of the rehearsal to use the toilet. Gian becomes the new King and takes back his role in the play, but alters the script such that he gets to shoot the prey with as many plungers as he wish, the prince doesn't marry the princess, and he even gets struck by lightning - literally.
