With pride and love as a mother, Eriko raised her daughter Mahiru on her own, and now that Mahiru has married and settled into family life, things should finally be peaceful. However, Mahiru's marriage begins to falter, and she confides in Eriko about her husband Tatsuro's infidelity. When Eriko confronts Tatsuro in person, he suddenly confesses, "I'm in love with you, my mother-in-law." From that day on, Tatsuro begins obsessively pursuing Eriko, entangling her in a twisted web of desire. Trying to preserve her dignity and love as a mother, Eriko attempts to reason with him, but the path ahead is anything but easy. This is the story of a mother torn between love and lust.