The film adapts and expands the Planetarian visual novel by Key. The story is set in a dystopian future where biological and nuclear warfare has left a once prosperous civilization in complete ruin. The film tells the story of an old man travelling around with a mobile planetarium projector to show people the stars.

In the year 2032, the legendary idol unit "7th Sisters" suddenly retired from the industry and disappeared. That was the end of the idol industry... until two years later, when a young glory-seeking employee is appointed to be the leader of Tokyo's next generation idol studio, "777 (Three Seven)," commonly referred to as Nanastar. However, the city continues to believe that idols are a thing of the past, and Nanastar is no exception. Their slump continues, but one day a mysterious and beautiful female manager approaches you and says, "If the idols of the past are gone, we'll just have to make new idols! True "sisters" linked by powerful bonds!" The story of the idols of the future, the Nanastar Sisters, will now unfold.

Miss Kobayashi, Tohru, Kanna, and Iruru's peaceful lives are shattered when Kanna's father, Kimun Kamui, leader of the Chaos Forces, arrives and forces her to return to the Dragon World to fix a past mistake. With a war brewing between Chaos and Harmony, Kanna must find a way to unite the two worlds but is torn between her loyalty to her friends and her father's demands. Miss Kobayashi, however, refuses to let her go and tries to mend Kanna and Kamui's broken bond. As dragons clash, Iruru uncovers a hidden force manipulating the war. Can they stop the war before it consumes both worlds?

Schoolboy Hinata has a big crush on his classmate Shigure, but is too shy to tell her. On the day Shigure is leaving, Hinata flies off on the wings of a bird chasing after her to tell how he feels!