Being forced in a room with someone you have barely an idea on is awkward.
Imagine being forced into a home with someone you've never met once in your entire life, and then finding out you're getting married once you're of legal age.
That's what has happened to Shin Hoseok, a 13 year old whose parents died in a disastrous car accident when he was the age of 3. He moved in with his grandmother and grandfather, but at his grandmother's late passing a year prior, his grandfather began to change. Drastically.
Before Hoseok was born, their family was in trouble. The Chae's were good friends with the family and easily stepped into help, but the Shin's insisted on repaying their debt to them.
By offering their unborn grandchild to be wed to Chae Hyungwon, the little 4 year old who just sat confusedly on the sofa during the entire discussion. When Hoseok's grandfather was starting to become dangerous to be around, Soo-Yun, Hyungwon's grandmother, stepped in and took Hoseok without skipping a beat.
She knew it was time for the boys to meet. 
Hyungwon is harsh.
Hoseok is confused and scared.
Funny feelings start to emerge
and it just might work out.