Naoki, a socially isolated student, begins a secret sexual relationship with his tutor, Nami. The situation escalates when Nami's mother, Mizuho, discovers the affair and decides to engage in her own illicit encounters with him. Naoki soon finds himself entangled in a risky double life, pursuing forbidden desires with both women while narrowly avoiding detection by Mizuho's husband.
After discovering her husband's infidelity, Mizuho finds emotional and physical solace in Nao. Their bond quickly evolves into a risky secret affair, leading to passionate encounters both at home and in public. Despite her guilt, Mizuho becomes increasingly addicted to Nao's affection, forever changing their family dynamic.
Nao and Mizuho-san deepen their illicit connection as Mizuho seeks solace from her failing marriage in Nao's arms. Their secret affair escalates from risky encounters at home to a daring tryst in a public dressing room, leading Mizuho to realize she is falling for Nao despite her family commitments.