宫田春海（菊池桃子）突然昏迷不醒，她从小一人养大的女儿宫田彩加（莲佛美沙子）正要和公司前辈桧山悠一（中村苍）结婚。苦恼不堪的女儿，却意外发现母亲和她高中时代同学交换日记的事情，在寻访中，她开始了解自己的母亲。

Miyata Ayaka (Renbutsu Misako), an office worker, sees her world collapse around her when her mother Miyata Harumi (Kikuchi Momoko) collapses due to illness and is left in a coma because of it. She then discovers that her mother kept a secret diary that she writes with her high school friends and that the lies she has told her have become evident, with nothing to lose. Ayaka will travel to Kaga, in Ishikawa Prefecture, her mother's hometown, to try to clarify the truth of the lie in her mother's secret diary.