Last year, Nayeon was 17 when she had a car accident on the way to her school. She had been in a coma for almost 3 months. The doctor confirmed that she had amnesia when she woke up and knew nothing about her friends who visited her except for her parents. Two days after, her parents brought a man who was the same age as her named Taeyong. They told her that he was her stepbrother since 2 years ago. Nayeon believed what her parents explained and tried to make herself closed with Taeyong. But as time went on, Nayeon had doubted on Taeyong. She'd never expected that her life went through everything with such a rude brother since she was 15. Nevertheless, she also felt protected whenever he was around, especially after both of them left their parents to study abroad. She started to wonder about him when her memories were slowly coming back but none of it were about Taeyong. She afraid that all this time, her parents lied to her. Day by day, she kept thinking, "he's my stepbrother, right?"