My girlfriend's younger sister (awkward, shy, and uninterested in sex) made her addicted to drugs and sex until she reached climax, becoming his sex toy. Yokomiya Nanami WAAA-181

At his girlfriend's house, he met her unfriendly younger sister, Yokomiya Nanami. Not only was she a recluse, but she was also very shy and had no interest in sex. He drugged her, made her take drugs, and had sex with her, turning her into a sex slave!