Revengeful Sex with My Queen: To get revenge on my always aloof and arrogant older sister, I gave her a 100-fold concentrated sex enhancer. The result was multiple orgasms, her vagina becoming utterly depraved, and even making me, her younger brother, erect. Kamiki Rei START-255

I hate my older sister. After our father was laid off, her income became the mainstay of our family's livelihood. From then on, she became the queen of the house, and we all became her servants. I borrowed a super-powerful libido enhancer from a friend and gave it to her, half as revenge and half as a joke. As a result, she had multiple orgasms, her vagina was completely ruined, and even I, as her younger brother, got an erection.