Yerin has been hiding the letter somewhere she thinks is safe from anyone's reach- her late mother's diary. It is an average size notebook which Yerin treasures the most.

         Every night Yerin would read the diary as if her mother is talking to her. She longs for her mother's presence. She knew even if they dont show it her father and her little sister Yuju, they miss her too.

      The diary that Yerin takes cares so much also now serves like a Pandora's Box since Sowon's letter for Sinb was kept there too.

    While reading the diary at night. Yuju called her sister for dinner. Yerin immediately went downstairs because their father dont like it if they dont eat together. Hence Yerin carelessly put the diary beside other books. 

    The next day Yuju went to Yerin's room to take her books. Yerin was still in the bathroom that time so she just shouted where the books are. Yuju grabs her books but unknowingly their mom's diary was included too, because it was thin it went unnoticed.

      Yuju carried her books to school. She saw Umji at the entrance and decided to go inside together. While they are walking hand and hand, the thin diary suddenly fell but because Yuju is unaware of its existence they didnt notice it.

     Then someone pick it up to return to Yuju but stop when a piece of paper suddenly fell from it.

     The content of the paper was suddenly revealed to her..