I Became a Saintly Player, and Now I've Had an Epiphany

Forced to bind herself to the Saintly System and repeatedly rescue people in a horror game, Song Zhenzhen can only stare at the heavens in exasperation. But as she goes along, she suddenly realizes that everyone around her is acting strangely. It turns out she is the villainess in a book, there only to make up the numbers for the heroine, Song Mingen.