Kokone Morikawa is a high school student living with her father, a talented but underemployed mechanic named Momotaro. She often drifts into a dream world called Heartland, where she transforms into a princess named Ancien, who possesses magical abilities. The imaginary land closely mirrors Kokone's reality, filled with robots, self-driving cars, and a fierce battle against an evil corporation. The line between Kokone's dreams and reality begins to blur as she discovers that the events in Heartland may hold clues to her past and her mother's mysterious death.

When Momotaro is suddenly arrested for stealing vital technology secrets related to self-driving cars, Kokone must unlock the secrets of her dreams to uncover the truth and save her father. As she dives deeper into both worlds, Kokone is pursued by agents of a powerful company intent on obtaining her father's technology. With the help of her childhood friend Morio, she embarks on a thrilling adventure that bridges the gap between dreams and reality, ultimately revealing deeper connections between the two.