Seo Yoomin is the best superintendent in Hanrim Art's High School. She's known for her best grades in the entire school and is also the well-known nerd in school too. Just that, she's not that shy type kind of nerd, or that kind of really weak nerd. No. 

Her type of nerd, is the kind to go and lecture people all day to spend their useful energy on studying. Smart peoples adore her or hate her for being smarter than them. Others will just hate her for a boring lectures and scoldings. 

Just then, till a newly transferred student came into her life. He's not the type to be a badass, or a good student. But he was on an average position. And to Yoomin, she really hate this Jung Ilhoon. 

She didn't know why, but she just does. 

And to Ilhoon, Yoomin was nothing but just another second mother who lectures him all day. But until one night, where he participated an event, a rapping contest. Now, Ilhoon is one A-M-A-Z-I-N-G rapper. He's a 10 out of 10 when he raps. No, a 100 out of 10 to that.

But then, while participating contest, he didn't know he would bump into someone. Who somehow he calls her his Rapping Angel. 

But just then, there was a giant secret behind this Rapping Angel of his. A secret that she wants to keep it away from the world. And Ilhoon wants to find out about it.