Ten years after her husband passed away, Shiori and Hiroaki had been living alone together, their relationship evolving into something far beyond that of a normal mother and son. They deeply loved each other, sharing an intimate bond and promising to stay together forever. However, when Hiroaki found a job and was transferred to Gunma, he left her behind. Overwhelmed by loneliness, Shiori's mental state began to deteriorate. Nearly two years had passed since Hiroaki's departure. Unable to endure the solitude any longer, Shiori made the decision to travel to him. Boarding a local train bound for Gunma, she set out on a journey, reminiscing about the warm, tender days they once shared, stepping forward into a new chapter of her life.