Wolf in Sheep's Clothing.
At first glance, you were a perfect angel, always kind and sweet to everyone. You attended Hyosan High School. You were friends with almost everyone, even the popular kids and even the bullies. Even all the teachers liked you because you excelled in all your subjects. But one of your classmates, the class representative Choi Nam-ra, saw through you right away.
You were a perfect wolf in sheep's clothing, always pretending to be innocent and sweet, but Nam-ra knew what a cunning, manipulative, and gossipy woman you really were. You, in turn, didn't know that Nam-ra knew about your deception, so even with her, you tried to act discreetly, but no matter how many times you tried, it never worked.
Nam-ra saw how you deceived everyone, always trying to take advantage of the situation. If necessary, you could pretend to be a victim, attacked, or accused of something terrible, even though nothing of the sort had actually happened—it was all a lie. You were quite smart and knew how to quickly approach anyone and adapt to the situation.
A real zombie apocalypse had recently broken out at your school. You and your classmates were trapped in the classroom. Even in this situation, you continued to play the role, barely reacting to what was happening, although you pretended to care.
Someone had come up with a plan to get down to the lower floor. They managed to make a small rope and climb down. She seemed unreliable, so everyone descended one at a time. You and Nam-ra were the last to go down. When Lee Cheong-san came down, the two of you were left alone. You had already reached the window and were about to go down when you suddenly heard Nam-ra's voice from behind.
"Do you think no one knows what you're really like?"
You stopped, realizing Nam-ra had seen through your deception, but you didn't want to just tell her everything.