Secret Friend (2020)

Secret Friend 2020 / 비밀친구 2020 / bimilchingu

Their secret rules! They prefer four, rather than three! The three people who have come to live together live in peace, enjoying sex with each other's needs. But one day, Min Ji meets Hyeon Soo, who she had a crush on when she was young. After hearing about Min Ji's situation, Hyeon Soo was looking for a place to board, and Hyeon Soo asked if he could board at Me Ri's. 
So four people live together in one house. Me Ri starts to think differently from the moment she sees Hyeon Soo. A year later, their cohabitation ended, and Min Ji and her boyfriend left. The couple also makes new plans. (Source: HanCinema)