Miyata Ayaka works at a stationery manufacturer and is engaged to her colleague Hiyama Yuichi. However, she is reluctant to inform her mother Harumi. Ayaka has lived apart from Harumi ever since they had a big argument when she was 20. Harumi has dodged the identity of Ayaka's father from the time she was a child. One day, Yuichi forces Ayaka to inform her mother, and Harumi appears at the company the next day to assess whether Yuichi will make a suitable husband. Yuichi happens to show up and she takes him to a pub. The two of them get along very well and it is decided that she will come for the wedding dress fitting. However, on that day, Harumi is rushed to hospital after collapsing from a sudden brain haemorrhage. She does not regain consciousness even after three months. Meanwhile, Ayaka learns about her mother's living will from a nurse and discovers that she had been exchanging diaries between her classmates from high school days. She travels to her mother's hometown of Kaga City in Ishikawa Prefecture with the diary as her guide. The lies and hard facts written in the diary by the women, lead her to true happiness.