Finding her hometown to be tiresome, Princess Saltorine "Sally" Aldike wishes to leave the kingdom of Aldarake in pursuit of adventure. When a lonesome, long-haired traveler named Mikoto Kibitsu helps Sally in an attempt to flee from the palace, her passion is further fueled. Sally asks him to take her on a journey, even after Mikoto warns her of the peril—something made more evident when a large group of ferocious oni appears before the kingdom. Revealing himself to be the demon slayer Momotaro, Mikoto deals with the threat and promptly leaves Sally behind.

One month later, Sally musters up the courage to leave behind royalty and embark on her long-desired journey, filled with a new resolve to find Mikoto once more. Despite realizing her ignorance of the dangers that lie beyond the kingdom's walls, Sally discovers more truths in the world that she had been oblivious to—including a hidden side of herself.