Yoko Matsumiya, a third-year junior high school student, is depressed before her high school entrance exam. As she gazes out at the sea from the top of a high hill, she sees many hands swaying in the waves. Looking closely, she sees girls in school swimsuits in the foreground, and girls in monpe pants and air raid hoods appearing from the sea behind them. After this incident, Yoko falls ill with a fever and goes to bed. The next day, she announces that she will not go to her hometown but to the faraway Hachimonji High School, leaving her mother and best friend dumbfounded and then...

According to the afterword of the Touen Shobo version, "The night I learned of a tragic accident in which some junior high school girls who were enjoying a swim in the sea had been swept away by high waves, I had a creepy dream in vivid color in which an old junior high school building emerged from the sea," and the tragedy of the Pacific War was superimposed on it, and the work was written in one go as a book.