Im Nayeon has an identical twin named Im Najeong who is a boy waiting for his debut. However, he met in an accident and Nayeon needs to replace him in the NCT U line up unit which is a very successful 3 member unit. Now, she was forced to act as her twin brother to pursue his dreams to find his mother. Will she successfully make it up as a boy? Or Will she hide her identity well by not get caught?

Nayeon is an innocent clever young girl Taeyong is a bad scary boy What will happen when they both bump into each other multiple times maybe it's fate?

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?"

After leaving South Korea; Nayeon, Taeyong, and Yuta begin their new lives in Los Angeles, California. With Taeyong's mother tracking them down it'll be a lot harder to live their lives. There will be challenges and decisions they must face. Will they have their happy ending?