The film revolves around three struggling actors Michio, Gunji, and Enoken, who share a house together. One day, they find a baby girl left with a letter from Michio's ex-girlfriend. They name the child "Don-chan" and embark on the journey of raising her, despite their initial confusion.

In 2012, Atsuya and his 2 childhood friends do something bad and run into an old general store. They decide to stay there until the morning. Late into the night, Atsuya sees a letter in the mailbox. The letter is addressed to the Namiya General Store and the letter was written by someone to consult about worries. Incredibly, the letter was written 32 years ago. The mailbox is somehow connected to the year 1980. Atsuya and his friends decide to write a reply and place their letter in the mailbox.

Shoji Segawa was a quiet and inconspicuous boy, but, for the first time, he is recognized by people after winning the National Middle School Shogi Tournament. At the age of 26, his dream of becoming a professional shogi player collapses due to an age restriction. After he quits playing shogi, he becomes desperate. With the support of his peers, including Yuya Suzuki, and his love of shogi, Shoji Segawa begins to play shogi again. A miracle happens to him.

With his marriage decided, Akio Koga returns to his hometown to share the news. As he feels a wave of nostalgia for the town, he is also reminded of Akira Misawa, a girl who disappeared back in high school. Akio has long been haunted by the thought that Akira’s disappearance might have been partly his fault. He reunites with Yuiko Oshiro, his homeroom teacher from high school—now a novelist—but… A girl who vanished without warning one day in the past. A man who, after a long time away, returns home and meets her again. Is she truly the same girl from back then? Or is she merely an illusion shown by the guilt he’s carried all these years? The more he tries to unravel the deepening mystery, the stronger his anxiety grows. Where will he ultimately arrive—and what awaits him there?