In the video, Lee Joon Gi is seen handling the scene professionally, even helping IU find the right angle for her face.
IU cracks up when he eagerly advises in between takes, “Don’t pull [your lips] away.”
With the filming day falling on IU’s birthday (May 16), Lee Joon Gi relays his best wishes to her through a video message where he jokes, “I think of that kiss as my birthday present to you. It was a gift given against your will and that only I liked.”
The staff also celebrate by surrounding IU while they sing her a birthday song and present her with a cake.
Throughout the video, the two lead actors are seen lightening up the mood on set as they chat and joke around.
Watch the behind-the-scenes footage below!