Due to her husband's work, Keiko was left alone at home day after day, her sexual frustration building steadily. To cope, she began pleasuring herself regularly. One day, her son brought home a man named Hashimoto, whom he had met at his part-time job. Seeing her previously lonely son opening up to someone, Keiko felt relieved and began treating Hashimoto warmly. However, everything changed when Hashimoto secretly overheard a phone call between Keiko and her husband, uncovering her emotional and physical dissatisfaction. His demeanor shifted dramatically, setting off unexpected ripples that would alter the course of her life.