ROYD-335 My innocent and extremely shy stepsister became super sensitive and prone to premature ejaculation after I harassed her every day, and now she's orgasming like crazy! She transforms into a perverted girl who orgasms like crazy with a vulgar look on her face. - Otonashi Suzu - Suzu Otonashi

My parents remarried, and I suddenly gained a stepsister. She's a shy girl who can't express her opinions, a timid girl who can't clearly say no to things she dislikes. But after constantly teasing her, her sensitivity increased dramatically, and she became unable to live without it. In the end, she came to me, her older brother, on her own, and this girl who was so withdrawn and couldn't even express her own opinions...