While You're At It summary:

Kang Sihwa was everyone's sun, always in the spotlight, and the people around Lee Eunseo were always jealous of her because of her special childhood friend Sihwa. One day, Sihwa, who had suddenly disappeared, returned a few years later. With the swaying of Eunseo’s heart and Sihwa’s unpredictable behavior. We have a special relationship, right? Don't you think so? But… I still want to ask. What are we both doing?