Ever since childhood, Ataru had always felt close to his mother's friend, Iori. When they reunite after a long time, he's captivated by her mature beauty and his hidden feelings grow stronger. Meanwhile, Iori, unsatisfied in her marriage and secretly lonely, can't resist giving in to Ataru, and they end up making passionate love. After their first encounter, both become addicted to the intense pleasure, beginning a secret, obsessive affair. Yet while Ataru desperately wants to continue their relationship, Iori struggles with guilt over betraying her friend by sleeping with her son. Torn between love and sin, desire and regret, their forbidden bond teeters on the edge.