Iwanaga Kokichi (nicknamed "Iwa-san") runs a small used bookstore and takes care of his daughter-in-law and grandson. He had lost his son, and it's still unclear whether his death was an accident or suicide. One day a blind girl, Adachi Akiko, comes to Iwa-san's store to sell some books from her late father's collection. She also brings a letter and an unfinished book titled "The Lonely Hunter".