Friends since birth, everything changed when Lee Taemin had to leave because his dad's work was elsewhere.

Taemin had always though his best friend, Son Naeun, had been a boy because of her extremely short hair. She didn't mind since she was just happy to have a friend. Naeun's hair grew pretty quickly, so she always got it cut every week, in fear that if Taemin found out she was girl, they wouldn't be friends anymore.

By the time Naeun and Taemin had started kindy in different countries, Naeun didn't care about cutting her hair anymore and left it to grow. Because of her immense beauty, even at such a young age, and her sweetness and cheerfulness, it was easy to see she was liked and loved by her fellow peers.

Ten years later, in their first year of high-school, Taemin returns, and attends the same school that Naeun does. He doesn't seem to remember her, but she knows full well who he is. However, she doesn't have the courage to tell him.

And then along comes the usual drama of high-school, with the addition of Taemin's previous girlfriend, who he never loved, his cousin and a whole bunch of interfering students.

When will Taemin realise? And what's that feeling they have for each other?