A former Japanese girl who was obsessed with maids is reincarnated into the world of an otome game as Melody. Unaware of this fact, she pursues her single-minded dream of becoming the world's most wonderful all-works maid and finds employment with the impoverished Count Rudleberg family in the kingdom of Théolas. With her incredibly powerful magic, which she believes is simply the result of hard work, Melody transforms the family's dilapidated mansion, brews luxury tea from cheap leaves, and handles everything from cleaning and serving to hunting and construction.

Melody remains completely oblivious to her true identity as the otome game's most powerful heroine and saint, and she shows no interest in the romantic storylines or the looming threat of the Demon Lord. Her only concern is her work, and this obsession unintentionally shatters the game's original destiny. Other reincarnated individuals, including the game's designated villainess who is now Melody's mistress Luciana, panic as Melody effortlessly solves every romantic route and major plot event without ever realizing it.

As the series progresses, the world continues to try forcing the otome game plot, creating new crises when old ones are resolved. Melody faces a crisis of faith when asked to define a perfect maid, and she struggles with having any free time as she knows nothing else but work. When a blight and poor harvest threaten her lady's domain, Melody cures the crops only to have the blight return, suggesting a dark force is determined to see the family and region destroyed. Another reincarnated Japanese girl, Maika, also enters this world searching for her lost brother, adding further complications to the already derailed narrative.

After Luciana has a brush with danger, Melody takes on her most daring mission yet: enrolling as a student at the Royal Academy under the guise of the lovely Cecelia to serve as a bodyguard. She quickly finds that being a maid, student, and protector all at once is a challenge even for her, especially while trying to maintain her cover. The series follows this fantasy of misunderstood work as Melody continues to unknowingly break the game's destiny while pursuing her proud identity as an all-works maid, with the plot becoming more serious as her omnipotence is challenged and her character is forced to grow.