The Starry Sky World, also known as planet Saman, is the home to the twelve Star Princesses who are based on the Zodiac Signs and maintain order in the universe. But when the Knot Raiders attack the Star Palace, princesses scatter themselves across the universe as the Princess Star Color Pens. Seeking to revive the princesses and avert the universe from being consumed in darkness, the aliens Lala and Prunus travel with the fairy Fuwa to Mihoshi Town on Earth where they meet the imaginative Hoshina Hikaru. Receiving a Star Color Pendant and one of the Star Color Pens, Hikaru transforms into the legendary PreCure, Cure Star. Joined by Lala and two other girls, Elena and Madoka, Hikaru leads the Star Twinkle PreCure as they seek to revive the Star Princesses and fight against the Knot Raiders.