Yumiko was cleaning her eldest son's room when she discovered a tissue soaked with semen. This triggered lewd fantasies, and she began masturbating right there. At that very moment, her eldest son Kazuhiko suddenly returned and caught her in the act, creating an awkward tension between them. That night, a forbidden relationship began to blossom between the two, gradually growing deeper. Then one day, their secret was uncovered by her younger son Kengo. How will this illicit love between mother and sons reach its conclusion?