A one-sided crush is like toxic dust—you know it’s killing you, but you keep breathing it in anyway. For 5 years and 120 days, Jung Dahee has been hopelessly in love with her childhood friend, Lee Beomseok. Getting shot down by him has practically become a daily routine, but she’s determined to break the cycle with a grand confession on the day of the CSATs. She had it all planned out. That is, until she accidentally stumbles upon a secret affair between her target crush… and her very own older sister.