Jung Hyemi, a bright bubbly kindergarten teacher who loves little children more than anything in the world. For her, little children's naive smile can enlighten her day. There's no such thing as a bad day.

Kim Taehyung, an heir to the Kim Trading Company, one of the biggest company in Korea. He is cold, rude, hard-headed and very hard to please. But what most people don't know is, his other identity as the vocalist of the famous underground hip-hop group 'BTS', by the name of 'V'

Zico, a famous underground rapper also the leader of Block B, is Hyemi's bestfriend/brother/bodyguard. Zico is very overprotective when it comes to Hyemi. Back in school, Hyemi was always bullied because of her quiet and nerdy look, and Zico will be the one who fought with her bullies.