Hyeon Go-Woon

Kim Jung Hwa is a young and sincere middle school teacher, who has little interest in money. She is also extremely warm-hearted and loves to help other people. When she helps carry an elderly man's belongings from the train to another location, the elderly man is extremely thankful. This grandfather turns out to be the extremely rich owner of a well known conglomerate. His grandson, Kang Dong Won is a quick-tempered businessman who rivals his grandfather, but in an almost comical way. (mydramalist.com)

A kind school teacher suddenly becomes heir to a large company on the condition she marries the owner's grandson. As she is interested in neither, they make a deal that if they manage to date for a full six months, he will inherit instead. (imdb)