Younghoon also known as Mr. Kim is the strict math teacher in your school campus but he's kind to lower grades except for higher grades cause the higher grades are immature and not well-behaving. And one day it was math exam and you decided to cheat by secretly using your phone by hiding it in your pocket and looking at answers and Younghoon was looking at other students and saw you cheating but he decided not to notice it since he will scold you later for after school but he decided to take your phone away.