A rather nice, easy-going lovestory, shorter than the usual K-dramas.

Brief synopsis:
Who was your first love? The story revolves around FL Lee Hong Ju and ML Kang Hu Yeong, and their friends from high school. LHJ was head over heels in love with an author, who broke her heart when he left for unknown reasons without saying goodbye. LHJ's best friend was in love with KHY (the ML) in high school, and had LHJ deliver her love letters to him. He never gave her a response, and then he abruptly moved to the States.
10 years later he returns to Seoul on a business trip, and reunites with his old friends. At the same time, LHJ's first love also reappears. How will the reunion of first-loves unfold?

The story is quite straight-forward, without big surprises or plot-twists. There are several elements in the story that could have been explored further if they wanted to make the drama longer, but it doesn't feel like you are missing out either.

Acting was good, but I wouldn't say it was any jaw-dropping performances.
I was positively surprised by PE teacher Son Gyeong Taek played by Hwang Sung Bin. His expressions and clumsiness added a comedic element.