Aru Hi, Burikko Akuyaku Reijou ni Narimashite.

Otome game otaku Manami Aizawa is pushed down a staircase to her death and wakes up as Camille Rhodolite, the three-year-old daughter of a marquis—who also happens to be the villainess of one of her favorite games! In this game, four factions—Spades, Diamonds, Clubs, and Hearts—come together to study at a magical academy, and depending on what route the heroine chooses, she faces one of four villainesses. Camille, also known as the Queen of Hearts, is the villainess of the Heart Route, and is a snobbish and possessive girl notorious for being artificially cute and childish. The original Camille was obsessed with Prince Royce Garnet, the King of Hearts, but the reincarnated one doesn't hold the same feelings. Rather than Royce's bride, wouldn't it be much more fun to be his bodyguard? Accompanied by Achille Jade—the Jack of Hearts—Camille decides to pursue her two passions in life instead: loyalty to Royce and mastering magic! [Written by MAL Rewrite]