I Was Reborn After NTRing the Whole World

A terrible, unscrupulous System brought me to an unfamiliar world from a novel and made the downright perverse demand that I cuckold all the male leads who had found their happy endings. After I completed the mission, the System didn't send me back to my original world. Due to circumstances beyond anyone's control, I became a girl and returned to the beginning of the story. Only this time, the male leads had all been reborn with their memories...