Mesu Haha ~Onna ni Natta Kaa-san~

Tomomi was widowed 3 years ago, and currently lives her just her son. He's the spitting image of his father, nearly a grown man. It gives her perverse, loin-tingling urges. When she thinks of him it's not the benevolent, sexless love of a parent, but the yearning of a woman for a man.

It's an unforgivable fantasy she knows society won't accept. But... that feeling overwhelms. The thing that is immoral and taboo.
Her throbbing heart and dripping loins inevitably open, lewdly... Day by day her secret thoughts spill further into reality...

[From DLsite English]