Yeonjun has a great life. He just graduated from university and immediately found a great job at a studio. Yeonjun lives in a great apartment in an expensive apartment complex, plays the guitar, loves his dog Chibi and eats in restaurants.

Just recently, Yeonjun even decided to propose to his girlfriend, whom he has been dating for more than four years. That is how they went on a pre-wedding trip to Yeonjun's girlfriend's hometown.

There he meets her parents, grandparents and... Her younger brother? Yeonjun's girlfriend never talked about her younger brother.