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.

Shimajiro, who helped an injured baby whale Kuu-chan, takes care of Kuu-chan who wants to return to her mother and keeps her in touch. In order to return Ku-chan, who was about to be sent to the aquarium, to her mother, Shimajiro rides on her back and sets out on a journey toward the southern sea.

In the middle of class at a certain school, Rumi Yokoi, a diligent student, has her in-class life turned upside down when her desk mate Toshinari Seki begins to play by himself at his desk in class. Although Rumi is irked by Toshinari's distracting yet intricate playtime, she finds herself being drawn into his interesting hobby. Never being able to focus, Rumi observes Seki's stunning ways of slacking off in class.