Hyperbola of Youth(1957)

Overview:

Myeong-ho (Hwang Hae), a middle school teacher who had grown up in poverty, and Bu-nam (Yang Hun), the first son of the president of a trading company, attend the same university. A doctor suggests that Bu-nam, who is sick due to overeating, and Myeong-ho, who suffers from malnutrition, should switch life styles for two weeks. While living in each other's house, they fall in love with each other's younger sister and get married at a joint wedding ceremony.