Moon Hayoung has always been the smart, sensible, and slightly less noticeable counterpart to her older sister, Dayoung. Always happy to let her sister soak up the limelight, she's more than surprised when her parents ship her off to Seoul Star Academy, one of the top performing arts schools in Korea. Hayoung, more comfortable with being behind the curtain than in front of it, finds herself into a lifestyle she'd only witnessed from afar. Scared, and virtually alone, Hayoung begins her stint at SSA and vows to keep her head down and out of trouble. All that would be easy, if she didn't have him to deal with.

Kim 'Kai' Jongin, resident lady killer and one of the top dancers at SSA, needs help. He's failing two of the four classes required for graduation, and if he doesn't straighten up and fly right soon, he also risks his chance at debuting with his friends at the end of the semester. Known for his charming personality and his finesse on the dance floor, he's used to getting what he wants. When the studious Hayoung is appointed his tutor, he thinks it'll be just as easy to charm her as it's been with every girl before her. Too bad for him, she's oblivious to his attempts.

Hayoung finds Kai to be smarter than his bad boy appearance lets on, and Kai finds Hayoung to be a bit more free spirited than her glasses and neat pigtails suggest. While they sometimes argue and Kai's friends tease them both relentlessly, ultimately its music where they connect and find in each other the friend they'd always needed. A music competition pits them against a rival school where both Hayoung and Kai have connections, and neither of them pretty.

With tensions rising and their friendship strained by forces beyond their control, the two find themselves struggling to make it through unscathed. Will Hayoung be able to find her voice and step out of the shadow of her sister? And when Kai starts to realize that maybe he actually likes it when she talks nerdy to him, it may be too late. Can he step up his game, make the grade, and get the girl?