Sister's Diary (1968)

Seong-ae returns from her four years in the USA. While she was gone, her sister had passed away. Seong-ae's young niece begins to believe that her aunt is really her mother and starts calling her 'Mom' much to Seong-ae's embarassment. She finds her sister's diary and begins to read it. From the entries there, she comes to fall in love with her brother-in-law. However, he is uncomfortable with the situation and asks Seong-ae to leave as quickly as possible