What if you have this feeling that you're in love with your guy best friend, Would you confess it to him? Or would you just let time make him notice it? You as Bae Suzy of Miss A and Exo K's Do Kyungsoo.

Ji Hyun and Lu Han are childhood friends, who used to spend every day playing with each other and even made a promise to never separate. But what happens when Ji Hyun's parents decide to move from Seoul, South Korea? What will happen if she returns years later? Is the friendship still there or was it eliminated the day she left?

To protect (actually, babysit) the most popular boy group of twelve gorgeous and flawless looking boys was their job. Get all the danger away from them, and make sure nothing happens to them. That was Girls' Generation's mission, as agents and spies. No affection and feelings must form during that period of time, but what will happen, when they suddenly fall for each other, and have to face their goodbyes once the mission finishes?