
The central character in this drama is Joon-hwan, a handsome man who knows how to make women happy. The two satellites around him are Eun-ji, a pure and beautiful idol trainee, and her charming older sister Sun-yeong, who is also Joon-hwan’s wife.
After being abandoned by her manager, Eun-ji feels disappointed in herself, and decides to return to her older sister Sun-yeong’s house, but also meets her first love Joon-hwan, who is now her brother-in-law. Everyone welcomes Eun-ji’s return, but they treat her in two different ways. While Eun-ji and her older sister have different opinions, Joon-hwan always tries to comfort her.
One day, Sun-yeong goes on a business trip for a week and wants her younger sister to try to overcome this difficulty. However, this is a great opportunity for Eun-ji and Joon-hwan to have some private time and reminisce about the good old days. The two of them crossed a line that should never be crossed and as time goes by, they fall deeper in love with each other. However, a week passes and Eun-ji even feels jealous of her sister because she wants Joon-hwan. Joon-hwan also feels confused and sad because the time to part is near. The two of them decide to create a memory that they want to spend with each other.