Having lost her husband at an early age, Asako devoted herself to raising her beloved son, working tirelessly to send him through college. Every year, mother and son would visit her husband's grave together on the anniversary of his passing. That year, however, her son made plans to stay overnight at a hot spring inn with her, intending it as a gesture of care. Though his intentions were pure and innocent, his strong, mature physique awakened long-dormant desires within her. Once ignited, her passion could not be contained, and the naive young man found himself unexpectedly drawn into his mother's lustful embrace. A story of a mother and son bond deepening in an entirely new, forbidden way.