One morning, 48-year-old business traveler Hiroshi Nakahara boards the wrong train—a recently built express to his old hometown. Upon arriving, he visits his mother's grave, where he is mysteriously transported back in time. Hiroshi finds himself 14 years old, with full adult foreknowledge of all that is to come. Hiroshi slowly embraces his ability to relive his youth differently and prepares to address the great mystery of his childhood: the disappearance of his father.