"I Was Reincarnated as the Villainess in an Otome Game" centers on a young woman who, after an accident, finds herself reincarnated as the antagonist of a popular otome game she once played. In the game, the villainess, Catarina Claes, is destined to face exile or death after her schemes to win the affection of the game’s male leads fail. Aware of her grim fate, the reincarnated Catarina resolves to avoid this outcome by altering her behavior and relationships with the key characters.

The story unfolds in a fantasy world where Catarina, now inhabiting the body of her younger self, uses her knowledge of the game’s events to navigate her new life. She befriends the game’s main heroine, Maria Campbell, and works to build positive relationships with the male leads, including Prince Geordo Stuart, Keith Claes, Alan Stuart, Nicol Ascart, and Sirius Dieke. Each character has a distinct personality and backstory tied to the game’s narrative, and Catarina’s interactions with them often deviate from the original plot, leading to unexpected developments.

Catarina’s primary goal is to avoid the "doom flags" that would trigger her downfall. Her efforts to change her fate involve acts of kindness, strategic decisions, and a genuine desire to protect those around her. However, her obliviousness to the romantic feelings developing among the male leads and Maria adds a layer of comedic misunderstanding to the story. The narrative balances humor, romance, and light drama as Catarina navigates her relationships while trying to secure a peaceful future.

The manga explores themes of redemption, self-determination, and the impact of one’s actions on others. Catarina’s journey is marked by her growth from a self-centered noble to a compassionate individual who values friendship and loyalty. The story also delves into the complexities of the game’s world, including political intrigue, magical elements, and the societal expectations placed on its characters. Through its engaging plot and well-developed cast, the series offers a fresh take on the isekai and otome game genres.