Momotarou Morikawa, a car mechanic and single father, raises his daughter Kokone following the tragic loss of his wife, Ikumi, in an accident that left him to care for their child alone. His quirky demeanor and mechanical prowess shine through his work repairing vehicles and electronics, as well as his guardianship of a fractured tablet housing self-driving technology—a project Ikumi developed before her death, later refined by Momotarou after her passing. The tablet’s origins trace to research rejected by Ikumi’s father, Isshin Shijima, chairman of Shijima Motors, from whom Momotarou and Ikumi fled years prior to elope, severing ties with the corporate dynasty.

This history resurfaces when Momotarou is arrested under fabricated charges of corporate espionage, exposing rival interests intent on seizing the tablet’s now-prized autonomous vehicle software, poised for demonstration at the Tokyo Olympics. The arrest forces Kokone to confront hidden truths about her family’s past.

Within the dream realm of Heartland, Momotarou’s alter ego, Peach, rides a motorcycle as a steadfast ally to Princess Ancien. Reality and fantasy intertwine through motifs like Momotarou’s jacket echoing Peach’s attire, a plush blue dog named Joy, and a motorcycle mirroring Heartland’s surreal landscapes—elements drawn from bedtime stories Momotarou crafted for Kokone. These tales allegorized Ikumi’s life and their mutual ambition to revolutionize transportation technology.

A climactic moment bridges both worlds: as Momotarou clutches Kokone during a perilous fall, his actions synchronize with Peach’s parallel struggle in Heartland, underscoring his dual role as protector and adventurer. Post-credits glimpses of his youthful romance with Ikumi and their joint experiments with early autonomous driving software further illuminate their bond and professional legacy.

Momotarou’s journey orbits secrecy—shielding Kokone from corporate greed and grappling with unresolved grief. His arc culminates in reconciling with Isshin, acknowledging mutual regrets, and entrusting Ikumi’s innovations to Kokone, ensuring her mother’s vision endures beyond corporate strife.