Yoo Seojin hates imperfection whilst Lee Sungyeol is filled with flaws. She cannot stand the sight of him although she has had eleven years to get used to his presence. It doesn't help that he's the school prankster so he is omnipresent: everywhere despite being absent. 

Lee Sungyeol can't help but notice Yoo Seojin, whom he secretly admires . He's aware that she doesn't like him, but he doesn't know why. Still, this doesn't stop him from coming up with all sorts of answers to his own unsaid question. After all, he epitomizes the very word "shortcomings".

But change is constant whereas anything that is not change itself is subject to change. So what would Seojin do with the fresh knowledge that the object of her animosity hates himself more than she could ever bring herself to? How would Sungyeol feel when he comes to learn of the insecurities the object of his admiration holds in the deepest crevices of her heart?