On the eve of her son's marriage, her mother became a woman.

Yuka has raised her son, Kosuke on her own. While gradually she began to feel evil about her son, who looks like her late husband, she was venting unfulfilled desires within herself. Meanwhile, Kosuke also secretly has more love for his mother than a parent and child, but he secretly spends his daily life hiding this. However, on the eve of his marriage, Yuka peers at him masturbating, saying, "It's the last night we spend together as mother and child..." and gently strokes his arching, erect cock. However, the two can't stop doing that, and are unable to hold back and are driven by taboo lust...