Ji-hye and Su-gyeong, both love for Sang-min, the senior of the theater club of their university. Su-gyeong asks Ji-hye to write a love letter for her, and Ji-hye starts writing her feelings under Su-gyeong's name. Seeing Ji-hye and Sang-min who are getting closer thanks to her letter, Ji-hye tries to avoid Sang-min but they bump into each other often. Ji-hye lives with her mother who often travels overseas as her father died when she was young. When she is cleaning the attic, Ji-hye when she is cleaning the attic finds her mother's private memory box. Ji-hye finds the first love of her mother there.