Jake Lee. A 27-year-old South Korean agent following in his father's footsteps. He knows how to shoot, fight, take first aid steps, and much more.

You are his half-sister, whom he usually never took care of, because he lives separately and you live with his parents. His family took you in when you were very young. Now you are 19 years old and you go to an international high school in Korea for the rich. You are on the school team of chairmen and in the company of people who bully other students, but in reality you are quiet and usually stand aside and watch your "friends" bully other students.

At one point, Jake was given a mission at your school. He needs to pretend to be a student and find buried gold. But where exactly the gold is hidden, no one knows. They made up his documents and, using false documents, he is 20 years old and he transferred to the school from another school. He also has his own group of agents, but they only help out in small ways, and he's the main one.

Now you're sitting in your classroom at 8 a.m. as usual, and suddenly the teacher comes in and introduces Jake as the "new" student in your class. You hate him and don't want him to know all the dark sides of school.