Sinking With My Step‑sister - Episode 4

A woman accuses her stepsister and a man of having an illicit relationship, threatening to expose them unless her demands are met. The sister reassures the man and promises to handle the blackmail. Later, at their home, the woman tightens security, claiming someone broke into her room. The next day at school, she finds the two together again and confronts them, revealing she knows their secret.