Tensei-saki ga Shoujo Manga no Shirobuta Reijou datta

When her grandfather informs her that their engagement has been annulled, a young woman suddenly regains the memories of her past life. With this awakening comes a startling realization: she has been reincarnated into the world of her favorite shoujo manga. Worse yet, she is not the heroine or even a prominent character. She is Britney, the chubby, sycophantic follower of the story’s primary villainess—a cruel noblewoman who will stop at nothing to torment the protagonist. Trembling as she recalls the grim narrative ahead, Britney remembers exactly how her character's story ends. When the villainess’s malicious schemes are finally exposed, she shifts the blame entirely onto Britney, leaving her loyal pawn to face execution in her place. Desperate to escape this doomed fate, Britney devises a simple yet crucial plan: she must never become the villainess’s follower in the first place. Because the antagonist surrounds herself exclusively with those she deems far uglier than herself, there is only one reliable way to be cast aside. To survive, Britney must transform her appearance and slim down. Her new goal is clear—before tragedy strikes, it is time to go on a diet.