Krystal has always been a dense person when it comes to love. But when she sets eyes on Kim Jong-in, or Kai, who is known for playing many girls' hearts, she immediately hates him and he instantly hates her. Soon, they play a game of pursuit; the first person to fall in love with the other, loses. They lay out moves to ensnare their opponent, but accidentally falls for each other instead. But Krystal's heart had always belonged to Chanyeol; they were each other's ideal matches and everyone approved of the couple. But here was someone else stirring something in her heart and she didn't know what to make of it. What will Krystal do as her heart seems to be wrenched into two pieces for two different people who both want to win her full heart?