MTL - The Enchanting Empress Dowager is Really Poisonous - Chapter 49

Upon meeting the girl who would become her adopted younger sister, the duke’s daughter Christina regained memories of her previous life. Through those memories, she learned that her new sister, Mishuli, was the heroine of a certain story. And though the story depicted a Christina who abused her sister, the real Christina turned into a siscon who spoiled Mishuli to no end.

After accidentally falling, she actually finds herself bound to a Second Female Lead Counter Attacking System!

Extras die every day in various ways in the game [Yo-Ma Great War 3].