Only in the House of Parvis can an "elementalist" be born. Blessed by the goddess of water, an elementalist has the power to protect the continent from the deplorable demon race and bring rain to the cursed, arid lands. Duke Ludwig Parvis received a prophecy stating that one sole elementalist would be born from his lineage—and his daughter, Keira, has spent her life preparing for this great responsibility, always yearning for her father's unattainable affection.

However, a girl named Cosette Weinberg suddenly appears, announcing herself as the duke's only daughter and the true elementalist, stealing everything from Keira. Eventually, Cosette's abilities somehow manifest—proving her claims—and Keira is hastily executed for deceiving the entire nation. But as if by magic, Keira awakens in the past, two months before Cosette's arrival and with her memories intact. Determined to prove her legitimacy, Keira attempts to enjoy life far from her distant father and prepares to expose Cosette's lies once she finally emerges from the shadows.