After being forced to work overtime for the umpteenth time in a month, Yukimura Rina drags herself home exhausted. The overworked systems engineer downloads an otome game for comfort, only to pass out and wake up as Ekaterina, the villainess of that very game. Rina recognizes her new life as Ekaterina Yulinova, a noble from the prestigious four-hundred-year-old Yulinova Dukedom. While the game scenario originally destined her for ruin, her primary concern shifts when she meets her new older brother, Alexei. He is handsome, kind, and responsible, but she immediately fears he will work himself to death just as she did in her past life.

The story is set in a fantasy empire where noble society closely follows the rules of the otome game. Ekaterina now has two clear goals: find a way to avoid the doom flags that would destroy her and protect her beloved new brother from the horrors of overwork. The original plot of the game is quickly derailed as she uses her modern common sense and knowledge to navigate noble politics. She befriends the heroine Flora instead of bullying her, catches the attention of Prince Mikhail, and begins applying her past life's business acumen to revitalize her family's estate. Early on, she introduces innovations like fountain pens and new fashion trends, which inadvertently raise her status even higher.

As the narrative progresses through several arcs, Ekaterina leaves the academy to manage her ancestral home, where she confronts lingering hostility from servants loyal to her cruel late grandmother. She later embarks on a pilgrimage to sacred mines, encountering monsters and a dragon who proposes marriage, which forces the buried personality of the original Ekaterina to resurface. When she returns to school, she organizes a musical evening, which brings her into conflict with Lydia Selesnoa, a rival noble who seeks to become the next empress. Throughout these events, the extremely close and G-rated bond between Ekaterina and Alexei remains the emotional core of the story, even as the protagonist remains oblivious to the romantic feelings of those around her.