Mahiru Watanabe has always dreamed of crossing the wall that divides the country into East and West. As the youngest daughter of the chief of state in the East, her life is tightly controlled. When she was young, her grandfather filled her heart with tales of the free-sprited people in the West, igniting a deep longing for a life beyond the restrictions she knows. But as she meets Kousei Satou, an ordinary boy from the West, she discovers that something more than freedom awaits on the other side.