In 2019 Y/N decides she’s not going to wait for a man and decides to get pregnant using a sperm donar. She has a party for her insemination, where her best friend Do Kyungsoo, gets black out drunk and accidentally ruins the sperm donar’s sample. In his drunken state he replaces it with his and forgets it happened. 7 years later when Y/N moved back to Seoul, Kyungsoo realizes just how much her son looks like him.