Hunter and Jiyu are neighbors in a luxury apartment building on Manhattan's Upper East Side. Jiyu is a 'shy girl' who loves reading, while Hunter is a popular tennis prodigy who can't sit still for a second. They are polar opposites. Though forced together by their mothers, Jiyu soon becomes indispensable to Hunter. Believing Jiyu is his 'good luck charm' because he wins every match she attends, Hunter insists on her presence. Jiyu, annoyed by his constant requests, comes up with a trick: she writes her name on her palm and kisses it, and sure enough, Hunter wins. As they grow closer under the pretense of this 'jinx,' a major tragedy strikes Jiyu as an adult. 'Jiyu Parker, you just sold yourself for $100,000.' Now, Jiyu uses Hunter to survive, while Hunter uses Jiyu for the sake of his jinx. In tennis, 'love' means zero. Amidst childhood memories, the fluttering excitement of youth, and a complex relationship tangled in misunderstanding and love-hate, the two play a dangerous game. Who will emerge as the winner?