2019年、冬。清水あき子(27歳)は、思い出を大事に生きている。 2009年、冬。清水あき子は自宅から自分の学力で通える最大限に遠い都内の高校に通っている。常に睡眠不足のあき子は家では眠ることができず、昔一緒に住んでいたおばあちゃんの家に行き、眠りにつく。相変わらず寝不足の電車内、あき子は吉田と出会う。What's most important in life always changes and goes away. Winter in 2009, Akiko Shimizu goes to high school in Tokyo as far from home as she can get in with her ability. She is in junior grade. She is always sleep deprived and cannot sleep at home. She goes to her grandma's house where she used to live together and falls asleep there. Akiko, in lack of sleep as usual, meets Yoshida in a train. Although she knows that they never understand each other, she falls in love with someone, spends some time together, and seperate. Even if it's been a mistake, Akiko Shimizu embraces the moment and falls asleep.