Lucienne, who was abused in the royal harem, regains memories of her past life after a head injury.
No way! Lucienne La Verier is the name of the villainous princess from the otome game she loved.
But wait, how old am I now? Isn't Lucienne's life way too hard from the start?

This story follows a young princess, who despite being royalty, has been oppressed (though she surprisingly doesn't mind much), and an assassin (with yandere tendencies) who gradually finds the pitiful princess adorable, as they become friends ten years before the original story.