Mukashi no Uwaki Aite no Ko ga Jitsu wa Watashi no Musuko no Doukyuusei de...

The ghost of Kanae's salacious past comes to haunt her in the form of Yusuke, a friend of her son's who reveals his father to be her partner from a past affair. Yusuke is obsessed with the sex tape Kanae and his father made, and Kanae agrees to have sex with him once to put it all behind her, but she's been lonely with her husband spending all his time at work, and her new suitor is VERY persistent...
(Source: Fakku!)
Note: A live-action AV adaptation (NIMA-041) was released on February 14th, 2025.