Akuyaku Reijou, Cecilia Sylvie wa Shinitakunai node Dansou suru Koto ni Shita.

Cecilia Sylvie was born with a silver spoon. Surrounded by sweets galore, wonderfully fine clothing, and spoiled rotten, she became an arrogant and selfish child. That was until, at five years of age, she realized that she was the villainess of an otome game she played in her previous life. Even worse, every ending leads to death! Resolved to turn her miserable fate around, Cecilia decides to become a man! Twelve years later, she enters an academy under the alias "Cecil," an unknown boy of lower nobility. All she wants is a peaceful school life, yet she finds herself at the center of attention anyway. Her female classmates are infatuated with her, the crown prince won't stop pestering "Cecil" about Cecilia, and the main heroine is acting entirely out of character. Having her hands full with all kinds of unexpected developments, can Cecilia keep her gender a secret and avoid a bad end? [Written by MAL Rewrite]