Yoo-jin is a party girl with lots of male acquaintance's, but no boyfriend. After a night of heavy partying she wakes up alone in a hotel-room certain that something happened last night. She then goes on a hunt for the missing guy.

Lead by matriarch widow Hong Duk-ja, the Hong gangster family turns legitimate, but a figure from their past returns to undermine and ruin their popular new business.

Mrs. Hong Duk-Ja quits the mafia and starts food company. She then goes on a overseas trip to Japan with her family. An incredible case then occurs.

How much do you know about your grown up son? In Mom’s Diary, the daily lives of the grown up celebrity sons are closely observed by their mothers. Do you know why your son drinks so much these days? How much do you know about your son’s philosophy in his life style? Heart-warming moments of observational communication between a mother and a son can be seen on Mom’s Diary.