The drama will center around Ma Yeo Jin (Ko Hyun Jung), a elementary teacher of the 6th grade and her students Shim Ha Na (Kim Hyang Gi), Oh Dong Goo (Chun Bo Geun) and Kim Seo Hyun (Kim Sae Ron) who are reveling against her. Teacher Ma is very realistic and to her elementary students, she shows how tough it is to live the world. Instead of being a shield for her students, she herself becomes the authority. She often pushes her students to the edge by blackmailing and mischief-making. Whole class of 6-3 (class 3 of the sixth grade) is rebelling against teacher Ma's educational attitude which is incomprehensible. Sometimes they would betray each other, sometimes they help each other and gradually they realize secret of the reality and make on their own views of the world. This kind of setting of the drama is totally new compared to the previous drama where the teachers were always the protectors of their students. Teacher Ma is trying to be the high wall for the students and her students are trying not to be defeated and overcome the highness of the wall. And such strong plot will touch the hearts of the viewers with massive emotions. Through the story to show the meaning of the true education and will make the viewers look back on the true meaning of the happiness.