取られん母 ～夏のある日、母さんは僕の親友の子供を身籠った～

Why? How did this happen? When did Mom and Nagi become intimate enough to have sex? Why is Mom pregnant with Nagi's baby instead of Dad's? I don't understand any of this.

No, I don't want to understand. As if to flaunt it to me, helpless and consumed by despair, Nagi thrusts his hips vigorously, taking my mother. My beloved mother, the most important person to me, has been taken by Nagi.

My gentle mother's eyes no longer look at me. They only look at Nagi. I can't forgive Nagi for having sex with Mom countless times behind my back and getting her pregnant! But Mom doesn't seem to mind in front of me.

Worse, she's accepting Nagi's penis with an expression of pleasure I've never seen before. Anger, hatred, despair... Amidst this jumble of emotions, I found myself intensely aroused by the sight of my mother, pleasured by my best friend, my own penis swelling with rage.

Nishino Riho is young, beautiful, and gentle. She possesses a voluptuous figure men adore—103cm I-cup breasts and a 99cm ample rear.

This mother cuckold story depicts how she betrayed her husband and their cherished only son, the protagonist “Nishino Ryota,” to drown in sex with Nagi, ultimately conceiving Nagi's child within her womb as a woman.

Driven by her lust, Riho surrenders to Nagi, a young, virile male brimming with sexual desire. Today, too, she steals glances from her beloved husband and son, drowning in carnal passion as she ripens.

[From official site]