Sehun is a manager of his own company. One day , Miss Yuri as Sehun's sister introduce a girl named Kim Yuna. Miss Yuri said that Sehun must have a secretary and she asked Yuna to be Sehun's secretary. Both of them started to be friends but Yuna didn't know that Sehun has a girlfriend that is BoA , the most famous kpop singer. Sehun started to fall in love with Yuna but he still love BoA. One day, when Sehun goes to BoA's house, he enters BoA and he saw BoA with another man inside the room. Sehun felt so angry and break up with her. He decided to confess his feeling to Yuna but sadly Yuna has di Wsappeard in the 4th of December.He look everywhere for Yuna but he still can't find her. What is thw reason Yuna left Sehun?what will happen to poor Sehun?