Hoshina Hikaru is a second-year middle school student who loves space! One night, as she was drawing some constellations, she met a mysterious fairy. She got warped to space for a little bit before waking up the next morning, thinking it was all a dream. But it wasn't so, so Hikaru proceeds to name the fairy "Fuwa". She meets two aliens: Lala and Prunce who came to Earth to find Fuwa but a bad alien, Kappard had followed them to get Fuwa first. But Hikaru transformed into the legendary warrior, Cure Star to protect Fuwa.

The rocket that Lala and Prunce were operating had gotten some damage, so Lala decided she'd try to repair it. Hikaru is surprised to hear Lala is 13 years old, like herself, but that Lala is also considered an adult back at home. At the same time, Lala was secretly upset that she couldn't become a Pretty Cure as well. As if he heard her doubts, Kappard appeared and was too tough for Star to handle on her own. So Star sends encouragement to Lala who was defending Fuwa. This helped give Lala some courage that led to her debut as Cure Milky!

Prunce deduces that the noise from the Star Color Pendant is related to the Star Princesses. As Hikaru tries to find where the noise leads to, she ends up butting heads with Lala, who wants to wait until her data analysis is complete. After receiving some advice from Elena Amamiya, a florist who is popular at Hikaru's school, Hikaru and Lala learn to stop arguing and listen to each other properly. Upon figuring out that the pendant is acting as a radar, the girls find a Star Color Pen, but it is swiped by another Notraider commander, Tenjou. With Tenjou defending herself with her Notray troops, Hikaru relies on Lala's help to get her through Tenjou's defenses and recover the Taurus Princess Star Color Pen. Using the pen's power, Fuwa revives the Taurus Star Princess, who urges the girls to help Fuwa grow and retrieve the other pens in order to save the universe. In the end, Hikaru and Lala apologize for their bad behavior and are forgiven.

Lala comes to Hikaru's school, where she observes how much everyone admires Elena for her sporty prowess. After briefly running into student council president Madoka Kaguya, who notices something peculiar about them, Hikaru and Lala go to thank Elena for helping them make up for their fight at her family's flower shop, where she looks after her many siblings. On their way home, Hikaru and Lala come under attack by Tenjou, who uses a smokescreen to keep them separated from each other. Having noticed the commotion, Elena rushes in to protect Fuwa, who gives her the power to transform into Cure Soleil and face Tenjou.

Madoka ends up discovering Fuwa and becomes conflicted over whether she should report her to her father Fuyuki, who is chief of the Diet's Space Research Special Task Force. As Hikaru and the others try to convince Madoka to stay quiet, they come across Tenjou, who attacks with overwhelming numbers of Notreys. Prioritising her own feelings over her father's wishes, Madoka strives to protect Fuwa and gains the power to become Cure Selene. After beating back Tenjou, Madoka keeps everyone's identity a secret from Fuyuki and vows to fight as a Precure.