My pregnant sister asked me to "just do it once," so I promised her I wouldn't tell anyone, and that's how I ended up having sex with her. (NHDTA-321)

The younger brother, who had always viewed his older sister as a sexual object, had been suppressing his rationality until now. However, upon hearing of her pregnancy, he took the opportunity to make his advances. While the older sister was surprised by her brother's sudden actions, she was also driven by unsatisfied desires…