A Japanese corporate slave, exhausted from her life of overwork, reincarnates as Fiona, the villainess of an otome game. Upon recognizing her new identity, she decides to abandon the game's script and pursue a quiet, happy slow life as a noble lady. When her fiancé, Prince Louis, expresses his desire to call off their engagement, she considers it a stroke of good luck. However, she soon uncovers the true reason the original Fiona was forced to act like a villainess: she is secretly very sick, which made navigating high society difficult. Determined to live a peaceful life alone, the new Fiona begins changing her daily habits, improving her diet, and being honest with those around her. To her great surprise, this sudden shift in behavior backfires spectacularly. Instead of drifting apart, Prince Louis becomes intensely devoted, declaring he loves her and has no intention of breaking the engagement. The story follows this chase-and-catch love comedy where the protagonist’s desire for a quiet life is constantly thwarted by her suddenly overprotective fiancé, whose actions deviate wildly from the original game's plot.

The story is set in a fantasy noble society reminiscent of an otome game, where social standing and royal engagements dictate one's future. The main characters are Fiona, a reincarnated woman whose practical desire for health and solitude clashes with her new role, and Prince Louis, whose unexplained change of heart turns him into a doting and persistent romantic lead. Notable narrative arcs include Fiona's initial adjustment to her sickly body and her secret efforts to regain her strength, the comedic and baffling escalation of Louis's affection as she tries to distance herself, and the overarching mystery of how her presence has altered the game’s original storyline.