It started out as a simple story. Boy meets girl. Boy likes girl. Girl likes boy. And then they date. But well, you can never predict where life takes you.  22 years old Shim Haeryung wanted the story to end simply too - for her and Zhang Yixing to get married as soon as she graduates from her college. Though somewhere, deep in her heart, she knew it would be hard to do, especially when she has a huge secret she's been keeping for so long. She would be doomed if one day Yixing knows about it - or at least that's what she thought. Haeryung is determined to find a solution to this problem of hers - afterall, she has to be the perfect companion for the perfect Zhang Yixing, a successful director at the early age of twenty-five. 

As Haeryung reach the final year of her college studies, things start to go out of the ordinary. A group of people that she wished she doesn't meet shows up randomly, keeping her secret became harder to do, and the sweet, romantic, and attentive Yixing she once knew... started to change. And turns out, he has a secret he's been keeping from her too? 

"It's impossible to know whether I am in love with you or the mask you wear for me."