Unrequited love. A feeling as suffocating and relentless as yellow dust in the air. Just like fine dust — you know it's bad for you, but you breathe it in anyway. That's exactly what one-sided love is. Five years and 120 days of silently loving her childhood friend. Rejected every single day as naturally as breathing, she still makes herself a promise: on the day her college entrance exams end, she will confess no matter what. But then one day, she witnesses something she can never unsee — her own older sister and the boy she's been in love with, meeting in secret.