Otome Game no Hametsu Flag shika Nai Akuyaku Reijou ni Tensei shiteshimatta...

After a hard knock to the head, Catarina Claes regains all of her memories from her previous life as a modern-day high schooler and realizes that she is now the selfish, haughty villainess character from an otome game that she was obsessed with. She immediately takes action in hopes of avoiding the destruction flags that doomed her character in the game: exile in the best case scenario and death in the worst.

One day, as Catarina is hard at work trying to avoid her own destruction flags, she's invited to a tea party hosted by the daughters of the marquis, the youngest of whom is Mary Hunt. While talking to Mary about her farming troubles, she finds out that Mary excels at gardening and quickly befriends her. Then Mary's betrothed, Alan Stuart, the fourth prince, suddenly shows up and demands a showdown with Catarina.

Catarina is immersed in a romance novel when she finds out she's been invited to a tea party hosted by Geordo and Alan at the palace. She's determined to find some fellow romance novel fans there to talk to. When she gets there, she meets Sophia, a beautiful girl scorned by others as a "cursed child" due to her unusual looks, and her brother Nicol, whose otherworldly beauty charms men and women alike.

Catarina finally meets Maria Campbell, the heroine of the otome game, and redoubles her efforts to avoid triggering her destruction flags. Maria's charming appeal leads Catarina to mistakenly believe that she's already conquered Geordo and Keith, so she calls for another of her now-habitual "mental meetings" to work out a strategy.

Catarina has completely fallen for Maria's charm, and she advances their friendship by coming to the rescue when some overbearing noble girls have Maria cornered in the school courtyard. Later, when Catarina visits a large farm for some pointers on a day off, she learns that Maria's family's house is close by and decides to pay a quick visit.

Catarina has successfully avoided triggering her own doom thus far, and now she's enjoying a summer vacation spent doing all kinds of preparations to avoid any future destruction flags, from practicing throwing toy snakes to working the fields to climbing trees. Then Geordo arrives and invites her to visit the lake, hoping to spend some time alone with her.

With summer vacation over, Catarina and the others are gearing up for a practical exam. The condition to pass is to retrieve a stone inhabited by magical power from the depths of some ancient ruins. Catarina teams up with Geordo, Keith, and Sophia to enter this complex dungeon filled with traps.

On her way to the east building library to find some reference books, Catarina joins up with the usual gang, and they decide to have a study session together. Then she opens a book that caught her eye... and it suddenly fills the room with light, then swallows her up along with Geordo and the others. Only Mary and Maria are left behind, so they cautiously open the book to try to rescue Catarina and the others trapped inside.

Anne Shelley is Catarina's personal maid, and is dedicated to serving her every need around the clock. Catarina is always surrounded by friends and laughter, but she's completely oblivious to the feelings that they have for her, which seems to have caused some misunderstandings. With no knowledge of how much Anne worries about this, Catarina decides to host Mary, Sophia, and Maria for a pajama party.

Catarina is suddenly faced with her own "judgment event." The cafeteria is abuzz, leaving Catarina's mind in a panic as she suspects her doom flag has been set at last. Then Geordo appears with the members of the student council. The noble girls continue to condemn Catarina as the student council members read the evidence they compiled against her. Then Maria, the alleged victim, speaks...

There's still no sign of Maria anywhere, and now Catarina has fallen into a deep sleep during which she dreams of her past life. Meanwhile, Geordo has a doctor examine her, but is disheartened when no cause can be found. As Catarina continues to sleep, all of her friends come to terms with their own feelings.

Catarina and the others have found the imprisoned Maria, and at last they confront the one behind her disappearance. How will this confrontation end?! Catarina has worked so hard to avoid her own doom flags all this time, and now she faces a crisis! And then the final event in the game, the graduation party, begins. Will Catarina make it through to the end without setting any doom flags?