Reborn into a novel, 5-year-old Mariette has spent her life on the run with her witch mom Yurie, who is desperate to save her daughter from the imperial temple's relentless witch hunt. But when Yurie finally dies from the mana that has overtaken her body, Mariette must fulfill a promise to watch over her new dad, the strong and cool Duke Descartes, who is destined by the story to be a slave of the temple. With the help of her witch protector Koon, can Mariette awaken her powers and save her dad?