The brother is a childish old man who stays at home playing with his cute little sister's body and making her his sex slave. He doesn't work and doesn't have the money to go to a brothel, so when his semen accumulates in his testicles, he calls his sister over and forces his fishy penis into her mouth, fucking her tight pussy without a contraceptive. The sister is reluctant, but her developed womanly body inevitably responds, and she twists her hips and becomes addicted to her brother's raw dick.