Bang Jongup is a son of Yongguk and Himchan, he is a arrogant boy and been spoiled by his parents too much. His parents love him so much since he is their only son. His family is rich and he always got what he want from his parents. He likes to bully a boy named Junhong that was in the same school as him, the reason he don't like Junhong is because the boy come from a poor family.

Jung Junhong is a son of Daehyun and Youngjae, he is a well-mannered boy. Eventhough his family is poor but they still happy. He is an obedient son, never ask too much thing from his parents even if he need it; he is already grateful that his parents can send him to school.

But...

What will happen when one day they found out that the're actually not their parents real son? They're exchanged.

In this story, Junhong and Jongup are in the same age and born on the same day x3