When a professor files a lawsuit against her over hand-written posters, university student Hye-ri goes to the clubroom to see her friend Min-young, with whom she made the poster. Finding her there with a new member, Hye-ri is caught up in an inner conflict.

Joo-young tries to call a friend on her birthday after a long time, only to find out that her number is not in use anymore. She spends all day to find her and learns some things she never knew about her lost friend up until now. Soon, the forgotten memory of that day comes back to her.