E Yi Jijie Jintian Ye Zai Koushixinfei

Story

Lin Anan was forced to bind to a villain system, reincarnating as Hera, the malicious stepsister in a Western fantasy novel. According to the plot, she must torment the kind-hearted “Cinderella” Duoliya, but each act of “bullying” secretly hides her protection of her. One day, an accident occurs: Duoliya’s tears trigger a system glitch—whenever Hela comes into contact with Duoliya’s bodily fluids, she loses control and speaks her true feelings. Though Duoliya appears fragile, she is actually a yandere.

Synopsis via AniList (English).