Akemi was abandoned by her husband and could no longer fulfill her role as the center of the household. In her loneliness, she came to rely on her son Shoji, raising him with deep affection. But that affection gradually crossed the boundary of mother and son, evolving into a physical relationship. As Shoji grew older, he began to feel their relationship was abnormal and slowly started avoiding sexual intimacy. Akemi, tormented by the fear that Shoji was drifting away from her, found their bond growing distant. Then, that autumn, as Shoji turned twenty, Akemi planned a hot spring trip to celebrate his coming of age, hoping to rekindle their connection and reclaim what they once had.